.lesson-check-backdrop{position:absolute;inset:0;z-index:25;display:flex;align-items:flex-start;justify-content:center;padding:16px 16px calc(var(--lesson-bar-clearance) + 16px);background:color-mix(in srgb,var(--scrim-ink) 28%,transparent);animation:lesson-check-fade .22s ease}.dark .lesson-check-backdrop{background:color-mix(in srgb,var(--shade-ink) 28%,transparent)}:where(.lesson-stage.is-fullscreen) .lesson-check-backdrop{padding-bottom:calc(var(--lesson-dock-clearance) + 16px)}.lesson-check-modal{--check-tint:var(--subject-tint);--check-ink:color-mix(in oklab,var(--subject-tint) 60%,var(--text));--check-solid:var(--check-ink);--check-on-solid:var(--ink-bright);position:relative;isolation:isolate;width:min(720px,92vw);height:auto;max-height:100%;display:flex;flex-direction:column;overflow:hidden;border-radius:24px;border:1px solid var(--border);background:color-mix(in srgb,var(--surface-solid) 86%,var(--card-glass));color:var(--text);outline:none;backdrop-filter:blur(24px) saturate(180%);-webkit-backdrop-filter:blur(24px) saturate(180%);box-shadow:var(--rim),var(--shadow-2);animation:lesson-check-rise .22s cubic-bezier(.22,1,.36,1)}.dark .lesson-check-modal{backdrop-filter:blur(24px) saturate(140%);-webkit-backdrop-filter:blur(24px) saturate(140%)}.lesson-check-modal[data-width=wide]{width:min(760px,94vw)}.lesson-check-modal[data-width=focus]{width:min(1040px,97vw);height:100%}.dark .lesson-check-modal{--check-on-solid:var(--background)}.lesson-check-modal[data-tone=success]{--check-tint:var(--feedback-correct-500);--check-ink:color-mix(in oklab,var(--ok) 78%,var(--text))}.lesson-check-modal[data-tone=review]{--check-tint:var(--feedback-caution-500);--check-ink:color-mix(in oklab,var(--warn) 78%,var(--text))}.lesson-check-aura{position:absolute;inset:0 0 auto 0;height:160px;z-index:0;background:linear-gradient(180deg,color-mix(in srgb,var(--check-tint) 12%,transparent),transparent);pointer-events:none}.lesson-check-head{position:relative;z-index:2;flex-shrink:0;display:flex;align-items:center;gap:12px;min-height:56px;padding:8px 14px 8px 16px;border-bottom:1px solid var(--border);background:color-mix(in srgb,var(--check-tint) 8%,transparent);transition:background .32s ease}.lesson-check-cta:focus-visible,.lesson-check-rail-pips button:focus-visible,.lesson-check-skip:focus-visible,.lesson-conf-chip:focus-visible,.lesson-hint-btn:focus-visible,.lesson-q-expand:focus-visible,.lesson-q-opt:focus-visible,.lesson-recheck-btn:focus-visible{outline:2px solid var(--check-ink,var(--brand));outline-offset:2px}.lesson-check-icon{display:flex;align-items:center;justify-content:center;flex-shrink:0;width:28px;height:28px;border-radius:10px;background:color-mix(in srgb,var(--check-tint) 18%,transparent);border:1px solid color-mix(in srgb,var(--check-tint) 34%,transparent);color:var(--check-ink);transition:background .32s ease,border-color .32s ease,color .32s ease}.lesson-check-titles{display:flex;flex-direction:column;flex:1 1 auto;min-width:0}.lesson-check-sub,.lesson-check-title{overflow:hidden;white-space:nowrap;text-overflow:ellipsis}.lesson-check-title{font-size:14px;font-weight:700;letter-spacing:-.01em;line-height:1.2;color:var(--check-ink);transition:color .32s ease}.lesson-check-sub{line-height:1.3}.lesson-check-chip,.lesson-check-sub{font-size:12px;color:var(--text-muted)}.lesson-check-chip{display:flex;align-items:center;gap:6px;flex-shrink:0;padding:5px 10px;border-radius:9999px;border:1px solid var(--border);background:var(--panel-fill-2);font-weight:600;white-space:nowrap}.lesson-check-chip[data-tone=review],.lesson-check-chip[data-tone=success]{border-color:color-mix(in srgb,var(--check-tint) 35%,transparent);background:color-mix(in srgb,var(--check-tint) 8%,transparent);color:var(--check-ink)}.lesson-check-rail-pips{display:flex;align-items:center;gap:8px;flex-shrink:0;max-width:100%;overflow-x:auto;scrollbar-width:none;padding:5px 8px;border-radius:9999px;border:1px solid var(--border);background:var(--panel-fill-2)}.lesson-check-rail-pips::-webkit-scrollbar{display:none}.lesson-check-rail-pips button:after{content:"";position:absolute;inset:-4px}.lesson-check-rail-pips button{position:relative;display:flex;flex-shrink:0;align-items:center;justify-content:center;width:36px;height:36px;border-radius:9999px;border:1px solid var(--border);background:var(--panel-fill-2);color:var(--text-muted);font-size:13px;font-weight:600;font-variant-numeric:tabular-nums;transition:background .16s ease,border-color .16s ease,color .16s ease}.lesson-check-rail-pips button[data-state=current]{border-color:color-mix(in srgb,var(--subject-tint) 55%,transparent);background:color-mix(in srgb,var(--subject-tint) 30%,transparent);color:var(--text)}.lesson-check-rail-pips button[data-state=correct]{border-color:color-mix(in srgb,var(--feedback-correct-500) 50%,transparent);background:color-mix(in srgb,var(--feedback-correct-500) 22%,transparent);color:var(--feedback-correct-700)}.dark .lesson-check-rail-pips button[data-state=correct]{color:var(--feedback-correct-100)}.lesson-check-rail-pips button[data-state=wrong]{border-color:color-mix(in srgb,var(--feedback-wrong-500) 50%,transparent);background:color-mix(in srgb,var(--feedback-wrong-500) 18%,transparent);color:var(--feedback-wrong-700)}.dark .lesson-check-rail-pips button[data-state=wrong]{color:var(--feedback-wrong-200)}.lesson-check-rail-pips button[data-state=answered]{border-color:color-mix(in srgb,var(--subject-tint) 35%,transparent);background:color-mix(in srgb,var(--subject-tint) 14%,transparent);color:var(--text-muted)}.lesson-check-body{position:relative;z-index:2;flex:0 1 auto;min-height:0;overflow-y:auto;overscroll-behavior:contain;padding:18px 20px 14px;display:flex;flex-direction:column;gap:14px}.lesson-check-locked{display:flex;align-items:center;gap:9px;padding:0 4px;font-size:12px;color:var(--text-muted)}.lesson-check-solution{border-radius:18px;border:1px solid color-mix(in srgb,var(--subject-tint) 24%,transparent);background:color-mix(in srgb,var(--subject-tint) 7%,transparent);padding:16px 18px}.lesson-check-solution-head{display:flex;align-items:center;gap:8px;margin-bottom:14px;font-size:13px;font-weight:700;letter-spacing:.02em;color:var(--text)}.lesson-check-solution-head svg{color:var(--subject-tint);flex-shrink:0}.lesson-check-solution-rule{flex:1;height:1px;background:linear-gradient(90deg,color-mix(in srgb,var(--subject-tint) 35%,transparent),transparent)}.lesson-check-foot{position:relative;z-index:2;flex-shrink:0;display:flex;align-items:center;gap:12px;padding:12px 16px;border-top:1px solid var(--border);background:color-mix(in srgb,var(--check-tint) 8%,transparent);transition:background .32s ease}.lesson-check-note{display:flex;align-items:center;gap:6px;min-width:0;font-size:12px;color:var(--text-muted)}.lesson-check-cta{display:inline-flex;align-items:center;justify-content:center;gap:7px;flex-shrink:0;height:44px;padding:0 20px;border-radius:9999px;border:1px solid transparent;background:var(--check-solid);color:var(--check-on-solid);font-size:14px;font-weight:600;transition:background .16s ease,transform .16s ease}.lesson-check-cta:hover:not(:disabled){transform:translateY(-1px)}.lesson-check-skip-wrap{display:flex;flex-direction:column;align-items:flex-start;min-width:0}.lesson-check-skip{display:inline-flex;align-items:center;flex-shrink:0;white-space:nowrap;min-height:44px;margin-left:-10px;padding:0 10px;border-radius:10px;border:none;background:transparent;color:var(--text-muted);font-size:14px;font-weight:600;text-underline-offset:3px;transition:color .14s ease}.lesson-check-skip:hover{color:var(--text);text-decoration:underline}.lesson-check-skip-note{margin:-8px 0 0;font-size:12px;line-height:1.35;color:var(--text-muted)}.lesson-check-cta:disabled{border-color:var(--border);background:var(--panel-fill-2);color:var(--text-muted);cursor:not-allowed}.lesson-q-card{position:relative;overflow:hidden;border-radius:18px;border:1px solid var(--border);background:var(--panel-fill);padding:16px 18px 18px;box-shadow:var(--shadow-1);transition:border-color .24s ease,background .24s ease,box-shadow .24s ease}.dark .lesson-q-card{box-shadow:none}.lesson-q-card[data-state=current]{border-color:color-mix(in srgb,var(--subject-tint) 35%,transparent);background:color-mix(in srgb,var(--subject-tint) 6%,transparent);box-shadow:0 0 0 1px color-mix(in srgb,var(--subject-tint) 12%,transparent),0 14px 40px color-mix(in srgb,var(--subject-tint) 12%,transparent)}.lesson-q-card[data-state=correct]{border-color:color-mix(in srgb,var(--feedback-correct-500) 28%,transparent);background:color-mix(in srgb,var(--feedback-correct-500) 6%,transparent)}.lesson-q-card[data-state=wrong]{border-color:color-mix(in srgb,var(--feedback-wrong-500) 26%,transparent);background:color-mix(in srgb,var(--feedback-wrong-500) 5%,transparent)}.lesson-q-meta{display:flex;align-items:center;flex-wrap:wrap;gap:8px;margin-bottom:12px}.lesson-q-spacer{flex:1 1 0;min-width:0}.lesson-q-num{display:flex;align-items:center;justify-content:center;width:22px;height:22px;border-radius:9999px;border:1px solid var(--border);background:var(--panel-fill-2);font-size:12px;font-weight:600;font-variant-numeric:tabular-nums;color:var(--text-muted)}.lesson-q-card[data-state=current] .lesson-q-num{border-color:color-mix(in srgb,var(--subject-tint) 55%,transparent);background:color-mix(in srgb,var(--subject-tint) 30%,transparent);color:var(--text)}.lesson-q-kind{font-size:12px;font-weight:700;letter-spacing:.08em;text-transform:uppercase;color:color-mix(in oklab,var(--subject-tint) 60%,var(--text))}.lesson-q-dot{width:3px;height:3px;border-radius:9999px;background:color-mix(in oklab,var(--text) 25%,transparent)}.lesson-q-pill{padding:3px 9px;border-radius:9999px;border:1px solid var(--border);background:var(--panel-fill-2);color:var(--text-muted);font-size:12px;font-weight:600;white-space:nowrap}.lesson-q-pill[data-tone=easy],.lesson-q-pill[data-tone=hard],.lesson-q-pill[data-tone=medium]{text-transform:capitalize}.lesson-q-pill[data-tone=easy]{border-color:color-mix(in srgb,var(--ok) 35%,transparent);background:color-mix(in srgb,var(--ok) 7%,transparent);color:color-mix(in oklab,var(--ok) 78%,var(--text))}.lesson-q-pill[data-tone=medium]{border-color:color-mix(in srgb,var(--warn) 35%,transparent);background:color-mix(in srgb,var(--warn) 7%,transparent);color:color-mix(in oklab,var(--warn) 78%,var(--text))}.lesson-q-pill[data-tone=hard]{border-color:color-mix(in srgb,var(--bad) 35%,transparent);background:color-mix(in srgb,var(--bad) 7%,transparent);color:color-mix(in oklab,var(--bad) 78%,var(--text))}.lesson-q-streak{display:flex;align-items:center;gap:5px;padding:3px 10px;border-radius:9999px;border:1px solid color-mix(in srgb,var(--feedback-nudge-500) 30%,transparent);background:color-mix(in srgb,var(--feedback-nudge-500) 14%,transparent);color:var(--feedback-nudge-700);font-size:12px;font-weight:700;white-space:nowrap}.dark .lesson-q-streak{color:var(--feedback-nudge-300)}.lesson-q-expand{position:relative;display:flex;align-items:center;gap:5px;padding:3px 10px;border-radius:9999px;border:1px solid color-mix(in srgb,var(--subject-tint) 40%,transparent);background:color-mix(in srgb,var(--subject-tint) 14%,transparent);color:color-mix(in oklab,var(--subject-tint) 60%,var(--text));font-size:12px;font-weight:600;white-space:nowrap;transition:background .14s ease}.lesson-q-expand:after{content:"";position:absolute;inset:-10px -4px}.lesson-q-expand:hover{background:color-mix(in srgb,var(--subject-tint) 24%,transparent)}.lesson-q-verdict{display:flex;align-items:center;gap:5px;font-size:13px;font-weight:700;white-space:nowrap;color:var(--text-muted)}.lesson-q-verdict[data-state=correct]{color:color-mix(in oklab,var(--ok) 78%,var(--text))}.lesson-q-verdict[data-state=wrong]{color:color-mix(in oklab,var(--bad) 78%,var(--text))}.lesson-q-text{font-size:17px;line-height:1.55;font-weight:500;margin-bottom:14px;text-wrap:pretty;color:var(--text);overflow-x:auto;overflow-y:hidden;padding-block:.15em;overscroll-behavior-x:contain}.lesson-q-facts{font-size:12px;color:var(--text-muted);white-space:nowrap}.lesson-q-task{margin:0 0 12px;font-size:13px;line-height:1.45;color:var(--text-muted)}.lesson-q-passage{margin-bottom:16px;padding:12px 16px;border-radius:12px;border:1px solid color-mix(in srgb,var(--feedback-info-500) 22%,transparent);background:color-mix(in srgb,var(--feedback-info-400) 6%,transparent)}.lesson-q-passage-head{margin:0 0 4px;font-size:12px;font-weight:700;letter-spacing:.06em;text-transform:uppercase;color:color-mix(in oklab,var(--feedback-info-700) 78%,var(--text))}.dark .lesson-q-passage-head{color:var(--feedback-info-300)}.lesson-q-ar,.lesson-q-passage-body{font-size:14px;color:var(--text)}.lesson-q-ar{margin-bottom:8px;padding:10px 16px;border-radius:12px;border:1px solid color-mix(in srgb,var(--brand) 22%,transparent);background:color-mix(in srgb,var(--brand) 8%,transparent)}.lesson-q-ar[data-part=reason]{border-color:color-mix(in srgb,var(--accent) 24%,transparent);background:color-mix(in srgb,var(--accent) 8%,transparent)}.lesson-q-opts{display:flex;flex-direction:column;gap:8px;margin-bottom:4px}.lesson-q-opts--row{flex-direction:row}.lesson-q-opt{display:flex;align-items:center;gap:12px;width:100%;min-height:50px;padding:10px 14px;border-radius:14px;border:1px solid var(--border);background:var(--panel-fill);color:var(--text);font-size:15px;text-align:left;transition:background .14s ease,border-color .14s ease,opacity .24s ease,transform .14s ease}.lesson-q-opt--tf{flex:1 1 0;justify-content:center;font-weight:600}.lesson-q-opt[data-state=idle]:hover:not(:disabled){border-color:color-mix(in srgb,var(--subject-tint) 40%,transparent);background:color-mix(in srgb,var(--subject-tint) 10%,transparent);transform:translateY(-1px)}.lesson-q-opt[data-state=selected]{border-color:color-mix(in srgb,var(--subject-tint) 45%,transparent);background:color-mix(in srgb,var(--subject-tint) 15%,transparent)}.lesson-q-opt[data-state=correct]{border-color:color-mix(in srgb,var(--feedback-correct-500) 50%,transparent);background:color-mix(in srgb,var(--feedback-correct-500) 14%,transparent);font-weight:600;box-shadow:0 0 0 1px color-mix(in srgb,var(--feedback-correct-500) 18%,transparent),0 8px 26px color-mix(in srgb,var(--feedback-correct-500) 13%,transparent)}.lesson-q-opt[data-state=wrong]{border-color:color-mix(in srgb,var(--feedback-wrong-500) 50%,transparent);background:color-mix(in srgb,var(--feedback-wrong-500) 12%,transparent)}.lesson-q-opt[data-state=dim]{opacity:.42}.lesson-q-opt-key{display:flex;align-items:center;justify-content:center;flex-shrink:0;width:26px;height:26px;border-radius:9px;border:1px solid var(--border);background:var(--panel-fill-2);color:var(--text-muted);font-size:12px;font-weight:600}.lesson-q-opt[data-state=correct] .lesson-q-opt-key{border-color:color-mix(in srgb,var(--feedback-correct-500) 50%,transparent);background:color-mix(in srgb,var(--feedback-correct-500) 28%,transparent);color:var(--feedback-correct-800)}.dark .lesson-q-opt[data-state=correct] .lesson-q-opt-key{color:var(--feedback-correct-100)}.lesson-q-opt[data-state=wrong] .lesson-q-opt-key{border-color:color-mix(in srgb,var(--feedback-wrong-500) 50%,transparent);background:color-mix(in srgb,var(--feedback-wrong-500) 24%,transparent);color:var(--feedback-wrong-900)}.dark .lesson-q-opt[data-state=wrong] .lesson-q-opt-key{color:var(--feedback-wrong-200)}.lesson-q-submit{display:inline-flex;align-items:center;gap:6px;height:44px;padding:0 16px;border-radius:9999px;border:1px solid color-mix(in srgb,var(--subject-tint) 45%,transparent);background:color-mix(in srgb,var(--subject-tint) 18%,transparent);color:var(--subject-tint);font-size:13px;font-weight:600;transition:background .14s ease,opacity .14s ease}.dark .lesson-q-submit{color:var(--tint-ink-pale)}.lesson-q-submit:hover:not(:disabled){background:color-mix(in srgb,var(--subject-tint) 28%,transparent)}.lesson-q-submit:disabled{opacity:.4;cursor:not-allowed}.lesson-q-count{margin-top:6px;text-align:right;font-size:12px;font-variant-numeric:tabular-nums;color:var(--text-muted)}.lesson-q-blank{display:inline-block;min-height:44px;padding:8px 10px;border-radius:10px;border:1.5px solid color-mix(in srgb,var(--text-muted) 55%,transparent);background:color-mix(in srgb,var(--brand) 5%,transparent);color:var(--text);font-size:16px;line-height:1.3;text-align:center;vertical-align:middle;outline:none;transition:border-color .14s ease,box-shadow .14s ease}.lesson-q-answer::-moz-placeholder,.lesson-q-blank::-moz-placeholder{color:var(--text-muted);opacity:1}.lesson-q-answer::placeholder,.lesson-q-blank::placeholder{color:var(--text-muted);opacity:1}.lesson-q-answer:focus,.lesson-q-blank:focus{border-color:var(--brand);box-shadow:0 0 0 3px color-mix(in srgb,var(--brand) 18%,transparent)}.lesson-q-blank[data-state=right]{border-color:var(--ok);background:color-mix(in srgb,var(--ok) 10%,transparent);color:var(--ok)}.lesson-q-blank[data-state=wrong]{border-color:var(--bad);background:color-mix(in srgb,var(--bad) 8%,transparent);color:var(--bad)}.lesson-q-blank-verdict{display:flex;align-items:center;gap:8px;margin-top:16px;font-size:14px;line-height:1.5}.lesson-q-blank-verdict[data-state=right]{color:color-mix(in oklab,var(--ok) 78%,var(--text))}.lesson-q-blank-verdict[data-state=wrong]{color:color-mix(in oklab,var(--bad) 78%,var(--text))}.lesson-q-blank-num{display:inline-flex;flex-shrink:0;align-items:center;justify-content:center;width:22px;height:22px;border-radius:6px;border:1px solid color-mix(in srgb,var(--brand) 45%,transparent);color:var(--brand);font-size:12px;font-weight:600}.lesson-q-blank-fix{margin-left:6px;white-space:nowrap;font-size:13px;font-weight:600;color:color-mix(in oklab,var(--ok) 78%,var(--text))}.lesson-q-answer{display:block;width:100%;min-height:88px;resize:none;padding:10px 14px;border-radius:12px;border:1.5px solid color-mix(in srgb,var(--text-muted) 55%,transparent);background:color-mix(in srgb,var(--brand) 5%,transparent);color:var(--text);font-size:16px;line-height:1.5;outline:none;transition:border-color .14s ease,box-shadow .14s ease}.lesson-q-answer[data-listening=true]{border-color:var(--bad)}.lesson-q-answer:disabled{color:var(--text-muted)}.lesson-q-answer.has-voice{padding-right:58px}.lesson-q-voice{position:absolute;right:6px;bottom:6px;display:flex;align-items:center;justify-content:center;width:44px;height:44px;border-radius:9999px;border:1px solid color-mix(in srgb,var(--brand) 30%,transparent);background:color-mix(in srgb,var(--brand) 12%,transparent);color:var(--brand);transition:background .14s ease}.lesson-q-voice:hover{background:color-mix(in srgb,var(--brand) 20%,transparent)}.lesson-q-voice[aria-pressed=true]{border-color:color-mix(in srgb,var(--bad) 40%,transparent);background:color-mix(in srgb,var(--bad) 14%,transparent);color:var(--bad)}.lesson-q-voice-note{display:flex;align-items:center;gap:6px;margin-top:6px;font-size:12px;color:var(--bad)}.lesson-q-voice-note.is-warn{color:var(--warn)}.math-keys{display:flex;gap:6px;overflow-x:auto;scrollbar-width:none;overscroll-behavior-x:contain}.math-keys::-webkit-scrollbar{display:none}.math-key{flex-shrink:0;min-width:44px;height:44px;padding:0 8px;border-radius:10px;border:1px solid var(--border);background:color-mix(in srgb,var(--brand) 6%,transparent);color:var(--text);font-size:17px;line-height:1;transition:background .14s ease}.math-key:hover{background:color-mix(in srgb,var(--brand) 14%,transparent)}.lesson-q-voice:focus-visible,.math-key:focus-visible{outline:2px solid var(--brand);outline-offset:2px}.lesson-q-strip{margin-top:14px;padding-top:13px;border-top:1px solid var(--border)}.lesson-conf-inline,.lesson-q-strip{display:flex;align-items:center;flex-wrap:wrap;gap:10px}.lesson-conf-label{font-size:12px;color:var(--text-muted)}.lesson-conf-row{display:flex;gap:6px}.lesson-conf-chip{height:44px;padding:0 12px;border-radius:9999px;border:1px solid var(--border);background:var(--panel-fill);color:var(--text-muted);font-size:12px;font-weight:600;transition:background .14s ease,border-color .14s ease,color .14s ease}.lesson-conf-chip:hover:not(:disabled){border-color:color-mix(in srgb,var(--subject-tint) 40%,transparent)}.lesson-conf-chip[aria-pressed=true]{border-color:color-mix(in srgb,var(--subject-tint) 45%,transparent);background:color-mix(in srgb,var(--subject-tint) 16%,transparent);color:var(--subject-tint)}.dark .lesson-conf-chip[aria-pressed=true]{color:var(--tint-ink-pale)}.lesson-conf-chip:disabled{opacity:.6;cursor:not-allowed}.lesson-hint-btn{display:flex;align-items:center;gap:5px;height:44px;padding:0 14px;border-radius:9999px;border:1px dashed color-mix(in oklab,var(--text) 22%,transparent);background:transparent;color:var(--text-muted);font-size:13px;font-weight:600;transition:color .14s ease,border-color .14s ease}.lesson-hint-btn:hover{color:var(--text);border-color:color-mix(in srgb,var(--feedback-nudge-400) 60%,transparent)}.lesson-hint-box{margin-top:14px;padding:11px 13px;border-radius:14px;border:1px dashed color-mix(in srgb,var(--feedback-nudge-400) 45%,transparent);background:color-mix(in srgb,var(--feedback-nudge-400) 8%,transparent)}.lesson-hint-head{display:flex;align-items:center;gap:6px;margin-bottom:5px;font-size:12px;font-weight:700;letter-spacing:.08em;text-transform:uppercase;color:color-mix(in oklab,var(--feedback-nudge-700) 78%,var(--text))}.dark .lesson-hint-head{color:var(--feedback-nudge-300)}.lesson-hint-body{font-size:13.5px;line-height:1.6;font-style:italic;color:var(--text)}.lesson-why{margin-top:14px;padding:12px 14px;border-radius:14px;border:1px solid color-mix(in srgb,var(--feedback-info-500) 28%,transparent);background:color-mix(in srgb,var(--feedback-info-400) 9%,transparent)}.lesson-why-head{display:flex;align-items:center;gap:6px;margin-bottom:6px;font-size:12px;font-weight:700;letter-spacing:.08em;text-transform:uppercase;color:color-mix(in oklab,var(--feedback-info-700) 78%,var(--text))}.dark .lesson-why-head{color:var(--feedback-info-300)}.lesson-why-body{font-size:14px;line-height:1.6;color:var(--text);text-wrap:pretty}.lesson-why[data-tone=recheck]{border-color:color-mix(in srgb,var(--feedback-nudge-500) 30%,transparent);background:color-mix(in srgb,var(--feedback-nudge-400) 9%,transparent)}.lesson-why[data-tone=recheck] .lesson-why-head{color:color-mix(in oklab,var(--feedback-nudge-700) 78%,var(--text))}.dark .lesson-why[data-tone=recheck] .lesson-why-head{color:var(--feedback-nudge-300)}.lesson-recheck-btn{display:inline-flex;align-items:center;gap:6px;margin-top:10px;min-height:44px;padding:6px 14px;border-radius:10px;border:1px solid color-mix(in srgb,var(--feedback-nudge-500) 35%,transparent);background:transparent;font-size:13px;font-weight:600;color:var(--text);cursor:pointer}.lesson-recheck-btn:disabled{opacity:.6;cursor:default}.lesson-why-marks{font-size:12px;font-variant-numeric:tabular-nums;letter-spacing:0}.lesson-marks-meter{display:flex;gap:3px}.lesson-marks-meter span{width:22px;height:5px;border-radius:9999px;background:color-mix(in oklab,var(--text) 14%,transparent)}.lesson-marks-meter span[data-filled=true]{background:var(--feedback-info-500)}.dark .lesson-marks-meter span[data-filled=true]{background:var(--feedback-info-400)}.lesson-answer-line{display:flex;align-items:baseline;flex-wrap:wrap;gap:6px;margin-top:10px;font-size:14px;color:color-mix(in oklab,var(--ok) 78%,var(--text))}.lesson-answer-line>span:first-child{font-weight:700}.lesson-answer-line--list{flex-direction:column;align-items:flex-start;gap:4px}.lesson-answer-line--list ul{margin:0;padding:0;list-style:none;display:grid;gap:4px;color:var(--text)}.lesson-answer-line--list li{display:flex;flex-wrap:wrap;align-items:baseline;gap:6px}.lesson-answer-line--list li>[aria-hidden]{color:var(--text-muted)}@media (max-width:640px){.lesson-check-backdrop{align-items:stretch;padding:8px 8px calc(var(--lesson-bar-clearance) + 8px)}.lesson-check-modal,.lesson-check-modal[data-width=focus],.lesson-check-modal[data-width=wide]{width:100%;height:100%;border-radius:20px;background:var(--surface-solid);backdrop-filter:none;-webkit-backdrop-filter:none}.lesson-check-body{flex:1 1 auto}.lesson-check-head{gap:8px;padding:8px 10px 8px 14px;flex-wrap:wrap}.lesson-check-icon,.lesson-check-sub{display:none}.lesson-check-body{padding:14px 14px 12px;gap:12px}.lesson-check-foot{padding:8px 10px 8px 12px;gap:10px;flex-wrap:wrap;row-gap:4px}.lesson-check-note{order:-1;flex-basis:100%}.lesson-check-foot[data-skippable]>.lesson-q-spacer{display:none}.lesson-check-skip-wrap{flex:1 1 0}.lesson-check-cta{padding:0 18px}.lesson-q-card{padding:14px 14px 16px;border-radius:16px}.lesson-q-text{font-size:15.5px}.lesson-q-opt{font-size:14px;min-height:46px}}.is-phone-landscape .lesson-check-backdrop{padding:8px 8px calc(var(--lesson-dock-clearance) + 8px)}.is-phone-landscape .lesson-check-modal,.is-phone-landscape .lesson-check-modal[data-width=focus],.is-phone-landscape .lesson-check-modal[data-width=wide]{width:100%;height:100%;border-radius:18px;display:grid;grid-template-columns:minmax(0,1fr) 188px;grid-template-rows:minmax(0,1fr) auto}.is-phone-landscape .lesson-check-body,.is-phone-landscape .lesson-check-focus{grid-column:1;grid-row:1/-1;min-height:0;border-right:1px solid var(--border)}.is-phone-landscape .lesson-check-body{padding:10px 12px;gap:10px}.is-phone-landscape .lesson-check-head{grid-column:2;grid-row:1;flex-direction:column;align-items:flex-start;gap:8px;min-height:0;padding:8px 10px;overflow-y:auto;border-bottom:none}.is-phone-landscape .lesson-check-head>.lesson-q-spacer,.is-phone-landscape .lesson-check-icon,.is-phone-landscape .lesson-check-sub{display:none}.is-phone-landscape .lesson-check-titles{flex:0 0 auto;width:100%}.is-phone-landscape .lesson-check-title{white-space:normal;display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical}.is-phone-landscape .lesson-check-rail-pips{flex-wrap:wrap;border-radius:16px}.is-phone-landscape .lesson-check-foot{grid-column:2;grid-row:2;flex-direction:column;align-items:stretch;gap:6px;padding:8px 10px 10px;border-top:none}.is-phone-landscape .lesson-check-foot>.lesson-q-spacer{display:none}.is-phone-landscape .lesson-check-note{order:-2;flex-basis:auto}.is-phone-landscape .lesson-check-cta{order:-1;width:100%;padding:0 12px}.is-phone-landscape .lesson-check-skip-wrap{flex:0 0 auto}.is-phone-landscape .lesson-check-skip-note{font-size:12px}.is-phone-landscape .lesson-q-card{padding:12px 13px 14px}.is-phone-landscape .lesson-q-text{font-size:15px;margin-bottom:10px}.is-phone-landscape .lesson-q-opt{font-size:14px;padding:8px 12px;min-height:44px}.is-phone-landscape .lesson-q-stem{font-size:13px}@keyframes lesson-check-rise{0%{transform:translateY(16px);opacity:0}to{transform:translateY(0);opacity:1}}@keyframes lesson-check-fade{0%{opacity:0}to{opacity:1}}@media (prefers-reduced-motion:reduce){.lesson-check-backdrop,.lesson-check-modal{animation:none}}.lesson-check-focus{position:relative;z-index:2;flex:1;min-height:0;display:flex}.lesson-q-meta--rail{margin-bottom:9px}.lesson-q-stem{font-size:15.5px;line-height:1.5;font-weight:500;text-wrap:pretty;color:var(--text)}.dd-board{margin:16px 0;padding:16px;border-radius:12px;border:1px solid var(--border);background:var(--panel-fill)}.dd-howto{margin-bottom:8px;font-size:13px;color:var(--text-muted)}.dd-pool{display:flex;flex-wrap:wrap;gap:8px;min-height:60px;margin-bottom:16px;padding:8px;border-radius:10px;border:1px dashed color-mix(in srgb,var(--text-muted) 45%,transparent);transition:background .14s ease,border-color .14s ease}.dd-pool[data-state=return]{cursor:pointer;border-style:solid;border-color:color-mix(in srgb,var(--brand) 55%,transparent);background:color-mix(in srgb,var(--brand) 5%,transparent)}.dd-pool:focus-visible{outline:2px solid var(--brand);outline-offset:2px}.dd-pool[data-hover=true]{border-color:var(--brand);background:color-mix(in srgb,var(--brand) 8%,transparent)}.dd-empty{width:100%;font-size:12px;text-align:center;color:var(--text-muted)}.dd-targets{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(100%,148px),1fr));gap:12px}.dd-targets>div{display:flex;flex-direction:column}.dd-targets .dd-target{flex:1 1 auto}.dd-target-label{margin-bottom:6px;font-size:13px;font-weight:600;color:var(--text)}.dd-target{min-height:80px;padding:8px;border-radius:10px;border:1px dashed color-mix(in srgb,var(--text-muted) 45%,transparent);transition:background .14s ease,border-color .14s ease}.dd-target[data-state=ready]{cursor:pointer;border-style:solid;border-color:color-mix(in srgb,var(--brand) 55%,transparent);background:color-mix(in srgb,var(--brand) 5%,transparent)}.dd-target[data-state=hover]{border-style:solid;border-color:var(--brand);background:color-mix(in srgb,var(--brand) 10%,transparent)}.dd-btn:focus-visible,.dd-chip:focus-visible,.dd-target:focus-visible{outline:2px solid var(--brand);outline-offset:2px}.dd-chip{display:inline-flex;align-items:center;gap:6px;max-width:100%;min-width:0;min-height:44px;padding:6px 12px;border-radius:10px;border:1px solid color-mix(in srgb,var(--brand) 30%,transparent);background:color-mix(in srgb,var(--brand) 7%,transparent);color:var(--text);font-size:14px;text-align:left;-webkit-user-select:none;-moz-user-select:none;user-select:none;cursor:grab;transition:background .14s ease,border-color .14s ease,box-shadow .14s ease}.dd-chip-label{min-width:0;overflow-wrap:anywhere;overflow-x:auto;overflow-y:hidden}.dd-chip:active:not(:disabled){cursor:grabbing}.dd-chip:disabled{cursor:default}.dd-chip-grip{color:var(--text-muted)}.dd-chip[data-state=selected]{border-color:var(--brand);background:color-mix(in srgb,var(--brand) 16%,transparent);box-shadow:0 0 0 1px var(--brand)}.dd-chip[data-state=right]{border-color:color-mix(in srgb,var(--ok) 55%,transparent);background:color-mix(in srgb,var(--ok) 9%,transparent)}.dd-chip[data-state=right] svg{color:var(--ok)}.dd-chip[data-state=wrong]{border-color:color-mix(in srgb,var(--bad) 55%,transparent);background:color-mix(in srgb,var(--bad) 8%,transparent)}.dd-chip[data-state=wrong] svg{color:var(--bad)}.dd-btn{display:inline-flex;align-items:center;gap:6px;min-height:44px;padding:0 14px;border-radius:9999px;border:1px solid var(--border);background:transparent;color:var(--text-muted);font-size:14px;font-weight:600;transition:background .14s ease,color .14s ease}.dd-btn:hover:not(:disabled){color:var(--text);background:var(--panel-fill-2)}.dd-btn--primary{border-color:transparent;background:var(--brand);color:var(--ink-bright)}.dark .dd-btn--primary{color:var(--background)}.dd-btn--primary:hover:not(:disabled){color:var(--ink-bright);background:var(--brand)}.dark .dd-btn--primary:hover:not(:disabled){color:var(--background)}.dd-btn:disabled{opacity:.5;cursor:not-allowed}.dd-board [data-verdict=right]{color:color-mix(in oklab,var(--ok) 78%,var(--text))}.dd-board [data-verdict=wrong]{color:color-mix(in oklab,var(--bad) 78%,var(--text))}.lesson-callout{--callout-tone:var(--feedback-info-500);--callout-ink:var(--feedback-info-700);border:1px solid color-mix(in srgb,var(--callout-tone) 32%,transparent);background:color-mix(in srgb,var(--callout-tone) 8%,transparent)}.dark .lesson-callout{--callout-ink:var(--feedback-info-300)}.lesson-callout[data-tone=caution]{--callout-tone:var(--warn);--callout-ink:var(--warn)}.lesson-callout[data-tone=brand]{--callout-tone:var(--brand);--callout-ink:var(--brand)}.lesson-callout[data-tone=teal]{--callout-tone:var(--palette-teal-600);--callout-ink:var(--palette-teal-700)}.dark .lesson-callout[data-tone=teal]{--callout-ink:var(--palette-teal-300)}.lesson-callout[data-tone=nudge]{--callout-tone:var(--feedback-nudge-500);--callout-ink:var(--feedback-nudge-700)}.dark .lesson-callout[data-tone=nudge]{--callout-ink:var(--feedback-nudge-300)}.lesson-callout-ink{color:color-mix(in oklab,var(--callout-ink) 80%,var(--text))}html[data-skin=classroom] .dd-board,html[data-skin=classroom] .lesson-q-card{border-radius:var(--skin-radius-card)}html[data-skin=classroom] :is(.lesson-q-opt,.lesson-q-blank,.dd-chip){border-radius:var(--skin-radius-btn)}html[data-skin=sketchbook] .dd-board,html[data-skin=sketchbook] .lesson-q-card{border-radius:var(--skin-wobble-a);border-width:var(--skin-line)}html[data-skin=sketchbook] .lesson-check-modal{border-radius:var(--skin-wobble-b);border-width:var(--skin-line)}html[data-skin=sketchbook] :is(.lesson-q-opt,.lesson-q-blank,.dd-chip,.dd-target,.dd-pool){border-radius:var(--skin-wobble-sm)}.lesson-slider{padding:12px 16px;border-radius:12px;border:1px solid var(--border);background:var(--panel-fill)}.lesson-slider-label{margin:0 0 4px;font-size:14px;color:var(--text)}.lesson-slider-row{display:flex;align-items:center;gap:12px}.lesson-slider-end{font-size:12px;font-variant-numeric:tabular-nums;color:var(--text-muted)}.lesson-slider-input{flex:1;min-width:0;height:44px;accent-color:var(--brand);background:transparent}.lesson-slider-input:focus-visible{outline:2px solid var(--brand);outline-offset:2px;border-radius:8px}.lesson-slider-value{margin:2px 0 0;text-align:center;font-size:18px;font-weight:700;font-variant-numeric:tabular-nums;color:color-mix(in oklab,var(--brand) 75%,var(--text))}.lesson-presentation-root.is-phone{--lp-ink:var(--ink-bright);--lp-shade:var(--palette-black);--lp-scrim:color-mix(in srgb,var(--lp-shade) 45%,transparent);--lp-scrim-edge:color-mix(in srgb,var(--lp-shade) 60%,transparent);--lp-scrim-band:color-mix(in srgb,var(--lp-shade) 44%,transparent);--lp-track:color-mix(in srgb,var(--lp-ink) 34%,transparent);--lp-fill:var(--subject-tint);--lp-bottom-h:82px;--lesson-bar-clearance:16px}.app-shell-lesson:has(.lesson-presentation-root.is-phone)>.app-header{display:none}.lesson-nowplaying-back{display:flex;flex-shrink:0;align-items:center;justify-content:center;width:44px;height:44px;margin-left:-8px;border-radius:12px;color:var(--text);transition:background .18s ease}.lesson-nowplaying-back:hover{background:color-mix(in srgb,var(--pal-primary) 8%,transparent)}.lesson-nowplaying-back:focus-visible{outline:2px solid var(--brand);outline-offset:-2px}.is-phone .lesson-video-chip-row{display:none}.is-phone .lesson-video-stage{padding:0}.is-phone .lesson-video-frame{min-height:0;border-radius:0}.is-phone .lesson-video-glow:before{display:none}.is-phone[data-phone-stage=video] .lesson-stage{background:var(--manim-canvas)}.is-phone[data-phone-stage=video] .lesson-blob-bg{display:none}.is-phone-portrait .lesson-console{flex-direction:column}.is-phone-portrait .lesson-stage-col{flex:0 0 auto}.is-phone-portrait[data-phone-stage=video] .lesson-stage{flex:none;width:100%;aspect-ratio:16/9}.is-phone-portrait[data-phone-stage=card] .lesson-stage-col{flex:3 1 0}.is-phone-portrait[data-phone-stage=full] .lesson-stage-col{flex:1 1 auto}.is-phone-portrait[data-phone-stage=full] .lesson-inline-panel{display:none}.lesson-inline-panel{--lp-inline-bar-h:48px;flex:1 1 0;min-height:0;display:flex;flex-direction:column;overflow:hidden;border-top:1px solid var(--border);background:var(--surface-solid);transition:flex-grow .32s cubic-bezier(.22,1,.36,1),flex-basis .32s cubic-bezier(.22,1,.36,1)}.is-phone-portrait[data-phone-stage=card] .lesson-inline-panel{flex:2 1 0}.is-phone-portrait[data-panel=min] .lesson-inline-panel{flex:0 0 calc(var(--lp-inline-bar-h) + env(safe-area-inset-bottom));padding-bottom:env(safe-area-inset-bottom)}.is-phone-portrait[data-panel=min][data-phone-stage=video] .lesson-stage-col{flex:1 1 0}.lesson-inline-bar{display:flex;flex-shrink:0;align-items:center;height:var(--lp-inline-bar-h);padding-right:4px}.lesson-inline-bar-toggle{display:flex;flex:1 1 auto;min-width:0;align-items:center;justify-content:space-between;gap:8px;height:100%;padding:0 8px 0 16px;color:var(--text-muted);text-align:left}.lesson-inline-bar-ask:focus-visible,.lesson-inline-bar-toggle:focus-visible{outline:2px solid var(--brand);outline-offset:-2px;border-radius:12px}.lesson-inline-bar-toggle .lesson-rail-eyebrow{overflow:hidden;text-overflow:ellipsis}.lesson-inline-bar-chevron{transition:transform .32s cubic-bezier(.22,1,.36,1)}.lesson-inline-panel[data-open=true] .lesson-inline-bar-chevron{transform:rotate(180deg)}.lesson-inline-bar-ask{display:flex;flex-shrink:0;align-items:center;justify-content:center;width:44px;height:44px;border-radius:12px;color:var(--subject-tint);transition:background .18s ease}.lesson-inline-bar-ask:hover{background:color-mix(in srgb,var(--pal-primary) 8%,transparent)}.lesson-inline-body{display:flex;flex:1 1 0;min-height:0;flex-direction:column;transition:opacity .2s ease}.lesson-inline-panel[data-open=false] .lesson-inline-body{opacity:0}.lesson-inline-panel .lesson-panel-scroll{padding:4px 16px 12px}.lesson-inline-panel .lesson-panel-composer{margin:0 12px calc(10px + env(safe-area-inset-bottom))}.is-phone .lesson-panel:not([data-open=true]){width:0;border-left-width:0}.is-phone .lesson-panel-spine{display:none}.is-phone .lesson-stage .lesson-caption{--lesson-caption-lift:10px;transition:transform .2s cubic-bezier(.22,1,.36,1)}.is-phone .lesson-stage[data-controls=shown] .lesson-caption{transform:translateY(calc(6px - var(--lp-bottom-h)))}.lp-video{z-index:30;color:var(--lp-ink);pointer-events:none}.lp-gesture,.lp-video{position:absolute;inset:0}.lp-gesture{pointer-events:auto;touch-action:manipulation;-webkit-tap-highlight-color:transparent}.lp-chrome{position:absolute;inset:0;opacity:1;transition:opacity .2s ease}.lp-video[data-visible=false] .lp-chrome{opacity:0}.lp-scrim{position:absolute;inset:0;pointer-events:none;background:linear-gradient(to top,var(--lp-scrim-edge) 0,var(--lp-scrim-band) var(--lp-bottom-h),transparent calc(var(--lp-bottom-h) + 48px)),var(--lp-scrim)}.lp-video[data-titled=true] .lp-scrim{background:linear-gradient(to bottom,var(--lp-scrim-edge) 0,transparent 88px),linear-gradient(to top,var(--lp-scrim-edge) 0,var(--lp-scrim-band) var(--lp-bottom-h),transparent calc(var(--lp-bottom-h) + 48px)),var(--lp-scrim)}.lp-video[data-notice=true] .lp-scrim{background:linear-gradient(to top,var(--lp-scrim-edge) 0,transparent var(--lp-bottom-h))}.lp-btn{position:relative;display:flex;flex-shrink:0;align-items:center;justify-content:center;width:44px;height:44px;border:none;border-radius:9999px;background:transparent;color:inherit;cursor:pointer;pointer-events:auto;transition:background .16s ease,opacity .16s ease;-webkit-tap-highlight-color:transparent}.lp-btn .material-symbols-outlined,.lp-play .material-symbols-outlined{text-shadow:0 1px 3px color-mix(in srgb,var(--lp-shade) 60%,transparent)}.lp-btn:hover:not(:disabled){background:color-mix(in srgb,var(--lp-ink) 14%,transparent)}.lp-btn:active:not(:disabled){background:color-mix(in srgb,var(--lp-ink) 22%,transparent)}.lp-btn:disabled{cursor:default;opacity:.38}.lp-btn:focus-visible,.lp-play:focus-visible{outline:2px solid var(--lp-ink);outline-offset:-2px}.lp-btn[data-on=true]:after{content:"";position:absolute;left:11px;right:11px;bottom:7px;height:2px;border-radius:1px;background:var(--lp-fill)}.lp-video[data-visible=false] :is(.lp-btn,.lp-play,.lp-seek){pointer-events:none}.lp-top{position:absolute;top:0;left:0;right:0;display:flex;align-items:center;gap:4px;padding:4px max(8px,env(safe-area-inset-right)) 4px max(8px,env(safe-area-inset-left))}.lp-title{flex:1 1 auto;min-width:0;overflow:hidden;font-family:var(--font-headline);font-size:15px;font-weight:700;line-height:1.3;white-space:nowrap;text-overflow:ellipsis;text-shadow:0 1px 3px color-mix(in srgb,var(--lp-shade) 60%,transparent)}.lp-centre{position:absolute;top:0;left:0;right:0;bottom:var(--lp-bottom-h);display:flex;align-items:center;justify-content:center;gap:clamp(20px,9vw,64px)}.lp-video[data-titled=true] .lp-centre{top:52px}.lp-video[data-notice=true] .lp-centre{display:none}.lp-skip{width:52px;height:52px;background:color-mix(in srgb,var(--lp-shade) 34%,transparent)}.lp-play,.lp-play-slot{width:60px;height:60px;flex-shrink:0}.lp-play{display:flex;align-items:center;justify-content:center;border:none;border-radius:9999px;background:color-mix(in srgb,var(--lp-shade) 46%,transparent);color:inherit;cursor:pointer;pointer-events:auto;transition:background .16s ease,transform .16s ease;-webkit-tap-highlight-color:transparent}.lp-play:active:not(:disabled){transform:scale(.94)}.lp-play:disabled{cursor:default;opacity:.38}.lp-bottom{position:absolute;left:0;right:0;bottom:env(safe-area-inset-bottom,0);height:var(--lp-bottom-h);padding:0 max(4px,env(safe-area-inset-right)) 0 max(4px,env(safe-area-inset-left))}.lp-row{position:absolute;left:max(4px,env(safe-area-inset-left));right:max(4px,env(safe-area-inset-right));bottom:38px;display:flex;align-items:center;height:44px;padding-left:8px}.lp-time{flex:1 1 auto;min-width:0;font-size:12px;font-weight:700;font-variant-numeric:tabular-nums;white-space:nowrap;text-shadow:0 1px 2px color-mix(in srgb,var(--lp-shade) 70%,transparent)}.lp-time-total{font-weight:500}.lp-seek{position:relative;display:flex;align-items:center;height:44px;cursor:pointer;pointer-events:auto;touch-action:none;--lp-seek-h:4px}.lp-video .lp-seek{position:absolute;left:max(12px,env(safe-area-inset-left));right:max(12px,env(safe-area-inset-right));bottom:0}.lp-seek[data-dragging=true]{--lp-seek-h:6px}.lp-seek[aria-disabled=true]{cursor:default}.lp-seek-track{position:relative;display:block;width:100%;height:var(--lp-seek-h);border-radius:9999px;background:var(--lp-track);transition:height .16s ease}.lp-seek-fill{top:0;bottom:0;left:0;border-radius:inherit}.lp-seek-fill,.lp-seek-thumb{position:absolute;background:var(--lp-fill)}.lp-seek-thumb{top:50%;width:14px;height:14px;margin:-7px 0 0 -7px;border-radius:9999px;box-shadow:0 1px 3px color-mix(in srgb,var(--shade-ink) 40%,transparent);transition:transform .16s ease}.lp-seek[data-dragging=true] .lp-seek-thumb{transform:scale(1.3)}.lp-seek[aria-disabled=true] .lp-seek-thumb{display:none}.lp-seek .lesson-dock-seg-marker{z-index:1;top:-3px;bottom:-3px;width:3px;margin-left:-1.5px}.lp-video .lp-seek .lesson-dock-seg-marker{background:color-mix(in srgb,var(--lp-ink) 92%,transparent)}.lp-video .lp-seek .lesson-dock-seg-marker[data-state=answered]{background:color-mix(in srgb,var(--lp-ink) 45%,transparent)}.lp-progress{position:absolute;left:0;right:0;bottom:0;height:3px;background:var(--lp-track);opacity:0;pointer-events:none;transition:opacity .2s ease}.lp-progress>span{display:block;height:100%;background:var(--lp-fill)}.lp-video[data-visible=false] .lp-progress{opacity:1}.lp-notice-layer{position:absolute;inset:0;z-index:31;container-type:size;pointer-events:none}.lp-notice-layer .lesson-notice{position:absolute;inset:0;align-items:center;pointer-events:auto;background:color-mix(in srgb,var(--scrim-ink) 32%,transparent)}:where(.dark) .lp-notice-layer .lesson-notice{background:color-mix(in srgb,var(--shade-ink) 45%,transparent)}.lp-notice-layer .lesson-notice-chip{position:absolute;top:8px;left:max(8px,env(safe-area-inset-left));margin:0;pointer-events:auto}.lesson-stage:has(.lp-video[data-titled=true]) .lp-notice-layer .lesson-notice-chip{top:56px}@container (max-width: 480px){.lp-notice-layer .lesson-notice-card{gap:4px;padding:10px 12px}.lp-notice-layer :is(.lesson-notice-icon,.lesson-notice-body){display:none}}.lp-ripple{position:absolute;top:0;bottom:0;z-index:1;width:38%;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:2px;overflow:hidden;pointer-events:none;background:color-mix(in srgb,var(--lp-shade) 64%,transparent);animation:lp-fade-in .12s ease}.lp-ripple[data-side=back]{left:0;border-radius:0 50% 50% 0/0 50% 50% 0}.lp-ripple[data-side=forward]{right:0;border-radius:50% 0 0 50%/50% 0 0 50%}.lp-ripple-wave{position:absolute;top:50%;left:50%;width:64px;height:64px;margin:-32px 0 0 -32px;border-radius:9999px;background:color-mix(in srgb,var(--lp-ink) 24%,transparent);opacity:0;animation:lp-ripple .52s cubic-bezier(.22,1,.36,1)}.lp-ripple-text{font-size:13px;font-weight:700;text-shadow:0 1px 2px color-mix(in srgb,var(--lp-shade) 70%,transparent)}@keyframes lp-ripple{0%{transform:scale(.2);opacity:1}to{transform:scale(3.4);opacity:0}}@keyframes lp-fade-in{0%{opacity:0}}.lp-strip{--lp-track:color-mix(in srgb,var(--lesson-meta-ink) 30%,transparent);--lp-fill:var(--lesson-solid);gap:2px;padding:4px max(8px,env(safe-area-inset-right)) 4px max(8px,env(safe-area-inset-left));border-top:1px solid var(--border);background:var(--surface-solid);color:var(--text-muted)}.lp-strip,.lp-strip-btn{display:flex;flex-shrink:0;align-items:center}.lp-strip-btn{position:relative;justify-content:center;width:44px;height:44px;border:none;border-radius:12px;background:transparent;color:inherit;cursor:pointer;transition:background .16s ease,color .16s ease}.lp-strip-btn:hover:not(:disabled){background:color-mix(in srgb,var(--pal-primary) 8%,transparent);color:var(--text)}.lp-strip-btn:disabled{cursor:default;opacity:.35}.lp-strip-btn:focus-visible{outline:2px solid var(--brand);outline-offset:-2px}.lp-strip-btn[data-on=true]{background:color-mix(in srgb,var(--subject-tint) 20%,transparent);color:var(--text)}.lp-strip-play{border-radius:9999px;background:var(--lesson-solid);color:var(--lesson-on-solid)}.lp-strip-play:hover:not(:disabled){background:color-mix(in oklab,var(--lesson-solid) 86%,var(--text));color:var(--lesson-on-solid)}.lp-strip .lp-seek{flex:1 1 auto;min-width:48px;margin:0 8px}.lp-strip-time{flex-shrink:0;margin-right:4px;font-size:12px;font-variant-numeric:tabular-nums;white-space:nowrap;color:var(--lesson-meta-ink)}@media (max-width:479.98px){.lp-strip-time{display:none}}.lp-sheet-layer{position:fixed;inset:0;z-index:90;display:flex;flex-direction:column;justify-content:flex-end;color:var(--text);pointer-events:auto}.lp-sheet-scrim{position:absolute;inset:0;border:none;background:color-mix(in srgb,var(--scrim-ink) 40%,transparent);cursor:pointer;animation:lp-fade-in .2s ease}.dark .lp-sheet-scrim{background:color-mix(in srgb,var(--shade-ink) 55%,transparent)}.lp-sheet{position:relative;width:100%;max-width:480px;max-height:86dvh;margin:0 auto;overflow-y:auto;padding:4px 8px calc(10px + env(safe-area-inset-bottom));border:1px solid var(--border);border-bottom:none;border-radius:20px 20px 0 0;background:var(--surface-solid);box-shadow:var(--shadow-2);animation:lp-sheet-rise .26s cubic-bezier(.22,1,.36,1)}.lp-sheet-grip{display:block;width:36px;height:4px;margin:6px auto 4px;border-radius:9999px;background:color-mix(in srgb,var(--text-muted) 45%,transparent)}.lp-sheet-title{display:flex;align-items:center;gap:8px;padding:8px 12px 6px;font-size:12px;font-weight:600;letter-spacing:.05em;text-transform:uppercase;color:var(--text-muted)}.lp-sheet-group{display:flex;flex-direction:column}.lp-sheet-opt{display:flex;width:100%;min-height:48px;align-items:center;justify-content:space-between;gap:12px;padding:0 12px;border:none;border-radius:12px;background:transparent;color:var(--text);font-size:15px;font-weight:600;font-variant-numeric:tabular-nums;text-align:left;cursor:pointer;transition:background .16s ease}.lp-sheet-opt:hover:not(:disabled){background:color-mix(in srgb,var(--pal-primary) 8%,transparent)}.lp-sheet-opt[data-active=true]{background:color-mix(in srgb,var(--subject-tint) 16%,transparent)}.lp-sheet-opt[data-active=true]>.material-symbols-outlined{color:var(--lesson-tint-ink)}.lp-sheet-opt:disabled{cursor:default;opacity:.45}.lp-sheet-opt:focus-visible{outline:2px solid var(--brand);outline-offset:-2px}.lp-sheet-opt-label{display:flex;align-items:center;gap:12px}.lp-sheet-rule{display:block;height:1px;margin:6px 12px;background:var(--border)}@media (max-height:500px){.lp-sheet-opt{min-height:44px}.lp-sheet-title{padding-top:4px}}@keyframes lp-sheet-rise{0%{transform:translateY(100%)}}@media (prefers-reduced-motion:reduce){.is-phone .lesson-stage .lesson-caption,.lesson-inline-bar-chevron,.lesson-inline-body,.lesson-inline-panel,.lp-btn,.lp-chrome,.lp-play,.lp-progress,.lp-seek-thumb,.lp-seek-track{transition:none}.lp-ripple,.lp-sheet,.lp-sheet-scrim{animation:none}.lp-ripple-wave{display:none}}.is-phone-portrait[data-panel=open][data-phone-stage=card]:has(.lesson-slide-cell[data-active=true] .lesson-3d-slide) .lesson-stage-col{flex:4 1 0}.is-phone-portrait[data-panel=open][data-phone-stage=card]:has(.lesson-slide-cell[data-active=true] .lesson-3d-slide) .lesson-inline-panel{flex:1 1 0;min-height:132px}:root{--tutor-orb-bottom:calc(28px + env(safe-area-inset-bottom, 0px));--tutor-orb-size:64px;--tutor-orb-clearance:0px}@media (min-width:1024px){:root[data-tutor-orb=visible]{--tutor-orb-clearance:calc(var(--tutor-orb-bottom) + var(--tutor-orb-size) + 16px)}:root[data-tutor-orb=visible] .tutor-orb-clear:after{content:"";display:block;flex-shrink:0;height:var(--tutor-orb-clearance);pointer-events:none}}.tutor-orb-clear{scroll-padding-bottom:var(--tutor-orb-clearance)}.liquid-glass.tutor-sheet{background:var(--surface-solid)}.liquid-glass.tutor-sheet,.liquid-glass.tutor-sheet:before{backdrop-filter:none;-webkit-backdrop-filter:none}.tutor-sheet:focus{outline:none}.parent-chat-scrim{animation:tutor-scrim-in .32s ease both}.parent-chat[data-state=closed] .parent-chat-scrim{animation:tutor-scrim-out .26s ease both}.parent-chat-panel{transform-origin:50% 100%;animation:tutor-genie-in .34s cubic-bezier(.32,.72,0,1) both}.parent-chat[data-state=closed] .parent-chat-panel{animation:tutor-genie-out .3s cubic-bezier(.32,.72,0,1) both}@media (min-width:1024px){.parent-chat-scrim,.parent-chat[data-state=closed] .parent-chat-scrim{animation:none;transition:opacity .24s cubic-bezier(.16,1,.3,1)}.parent-chat[data-state=closed] .parent-chat-scrim{opacity:0;transition-duration:.18s}.parent-chat-panel,.parent-chat[data-state=closed] .parent-chat-panel{animation:none;transform-origin:50% 50%;transition:transform .26s cubic-bezier(.16,1,.3,1),opacity .2s cubic-bezier(.16,1,.3,1)}.parent-chat[data-state=closed] .parent-chat-panel{opacity:0;transform:translateY(8px) scale(.98);transition-duration:.18s}@starting-style{.parent-chat-scrim{opacity:0}.parent-chat-panel{opacity:0;transform:translateY(16px) scale(.96)}}}@media (min-width:1024px) and (prefers-reduced-motion:reduce){.parent-chat-panel,.parent-chat[data-state=closed] .parent-chat-panel{transform:none;transition:opacity .15s ease-out}@starting-style{.parent-chat-panel{transform:none}}}.tutor-icon-btn{display:flex;flex-shrink:0;align-items:center;justify-content:center;width:44px;height:44px;border-radius:999px;color:var(--text-muted);transition:background-color .16s ease,color .16s ease}.tutor-icon-btn:hover{background:color-mix(in srgb,var(--text) 7%,transparent);color:var(--text)}.tutor-icon-btn.is-labelled{width:auto;gap:6px;padding:0 12px;font-size:13px;font-weight:600}.tutor-icon-btn[aria-pressed=true]{color:var(--brand)}.tutor-context,.tutor-empty-context{display:flex;align-items:center;gap:8px;font-size:13px;line-height:1.4;color:var(--text-muted)}.tutor-context{flex-shrink:0;padding:8px 12px;border-radius:12px;border:1px solid color-mix(in srgb,var(--brand) 22%,transparent);background:color-mix(in srgb,var(--brand) 7%,transparent)}.tutor-empty{display:flex;flex:1;flex-direction:column;align-items:center;justify-content:center;gap:12px;padding:0 16px;text-align:center}.tutor-empty-title{max-width:22rem;font-family:var(--font-headline);font-size:17px;font-weight:700;line-height:1.35;color:var(--text);text-wrap:balance}.tutor-convo.is-big .tutor-empty-title{font-size:21px}.tutor-empty-context{justify-content:center;text-align:left}.tutor-bubble-user{min-width:0;padding:11px 15px;border-radius:18px 18px 6px 18px;background:linear-gradient(135deg,var(--pal-primary),var(--pal-primary-container));color:var(--pal-on-primary);font-size:15px;line-height:1.55}.tutor-bubble-ai{padding:13px 15px;border-radius:18px 18px 18px 6px;border:1px solid var(--border);background:color-mix(in srgb,var(--brand) 4%,transparent);color:var(--text);font-size:15px;line-height:1.6}.tutor-convo.is-big .tutor-bubble-ai,.tutor-convo.is-big .tutor-bubble-user{padding:14px 18px}.tutor-thinking{display:flex;align-items:center;gap:10px;min-height:24px;font-size:14px;color:var(--text-muted)}.tutor-thinking-dots{display:inline-flex;gap:4px}.tutor-thinking-dots span{width:6px;height:6px;border-radius:999px;background:var(--brand);animation:lg-blink 1.2s ease-in-out infinite}.tutor-thinking-dots span:nth-child(2){animation-delay:.2s}.tutor-thinking-dots span:nth-child(3){animation-delay:.4s}.tutor-turn-note{display:flex;flex-wrap:wrap;align-items:center;gap:8px 12px;width:100%;padding:8px 8px 8px 14px;border-radius:14px;border:1px solid var(--border);font-size:14px;line-height:1.45;color:var(--text-muted)}.tutor-turn-note.is-bad{border-color:color-mix(in srgb,var(--bad) 40%,transparent);background:color-mix(in srgb,var(--bad) 8%,transparent);color:var(--text)}.tutor-retry{display:inline-flex;flex-shrink:0;align-items:center;gap:6px;min-height:44px;padding:0 16px;border-radius:999px;border:1px solid color-mix(in srgb,var(--brand) 45%,transparent);background:var(--surface-solid);color:var(--text);font-size:14px;font-weight:700;transition:background-color .16s ease}.tutor-retry:hover:not(:disabled){background:color-mix(in srgb,var(--brand) 12%,var(--surface-solid))}.tutor-retry:disabled{opacity:.5}.tutor-status{display:flex;align-items:center;gap:8px;margin-bottom:8px;padding:8px 12px;border-radius:12px;border:1px solid color-mix(in srgb,var(--warn) 40%,transparent);background:color-mix(in srgb,var(--warn) 9%,transparent);font-size:13px;line-height:1.4;color:var(--text)}.tutor-status>.material-symbols-outlined{color:var(--warn)}.tutor-status.is-bad{border-color:color-mix(in srgb,var(--bad) 40%,transparent);background:color-mix(in srgb,var(--bad) 8%,transparent)}.tutor-status.is-bad>.material-symbols-outlined{color:var(--bad)}.tutor-chip{min-height:44px;padding:0 16px;border-radius:999px;border:1px solid var(--border);background:var(--surface-solid);color:var(--text);font-size:13px;font-weight:600;white-space:nowrap;transition:border-color .16s ease,background-color .16s ease}.tutor-chip:hover{border-color:var(--brand);background:color-mix(in srgb,var(--brand) 8%,var(--surface-solid))}.tutor-composer{display:flex;align-items:center;gap:4px;padding-top:4px;padding-right:4px;padding-bottom:4px;border-radius:999px;border:1px solid var(--border);background:var(--surface-container-low);transition:border-color .2s ease,box-shadow .2s ease}.tutor-composer:focus-within{border-color:var(--brand);box-shadow:0 0 0 3px color-mix(in srgb,var(--brand) 14%,transparent)}.tutor-input{min-width:0;min-height:44px;flex:1;border:none;background:transparent;color:var(--text);font-size:16px;outline:none}.tutor-input::-moz-placeholder{color:var(--text-muted)}.tutor-input::placeholder{color:var(--text-muted)}.tutor-send{display:flex;flex-shrink:0;align-items:center;justify-content:center;width:44px;height:44px;border-radius:999px;background:linear-gradient(135deg,var(--pal-primary),var(--pal-primary-container));color:var(--pal-on-primary);transition:transform .2s ease,opacity .2s ease}.tutor-send:hover:not(:disabled){transform:scale(1.05)}.tutor-send:disabled{opacity:.45}.tutor-send.is-stop{background:var(--surface-solid);border:1.5px solid var(--text-muted);color:var(--text)}.tutor-chip:focus-visible,.tutor-icon-btn:focus-visible,.tutor-new-chat:focus-visible,.tutor-retry:focus-visible,.tutor-send:focus-visible,.tutor-thread:focus-visible,.voice-ghost:focus-visible,.voice-recording:focus-visible{outline:2px solid var(--brand);outline-offset:2px}.tutor-new-chat{display:flex;flex-shrink:0;align-items:center;justify-content:center;gap:8px;min-height:44px;border-radius:999px;border:1px solid color-mix(in srgb,var(--brand) 30%,transparent);background:color-mix(in srgb,var(--brand) 10%,transparent);color:var(--text);font-size:14px;font-weight:700;transition:background-color .16s ease}.tutor-new-chat:hover{background:color-mix(in srgb,var(--brand) 18%,transparent)}.tutor-rail-group{padding:0 4px;font-size:12px;font-weight:700;letter-spacing:.04em;text-transform:uppercase;color:var(--text-muted)}.tutor-thread{display:flex;flex-direction:column;gap:2px;min-height:44px;padding:8px 10px;border-radius:12px;border:1px solid transparent;text-align:left;transition:background-color .16s ease,border-color .16s ease}.tutor-thread:hover{border-color:var(--border);background:color-mix(in srgb,var(--text) 4%,transparent)}.tutor-thread[aria-current=true]{border-color:color-mix(in srgb,var(--brand) 30%,transparent);background:color-mix(in srgb,var(--brand) 10%,transparent)}.tutor-thread-title{min-width:0;flex:1;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;font-size:14px;font-weight:600;color:var(--text)}.tutor-thread-meta,.tutor-thread-preview{overflow:hidden;text-overflow:ellipsis;white-space:nowrap;font-size:12px;color:var(--text-muted)}.tutor-thread-meta{font-weight:600;font-variant-numeric:tabular-nums}.voice-ghost{transition:background-color .16s ease,color .16s ease}.voice-ghost:hover:not(:disabled){background:color-mix(in srgb,var(--text) 7%,transparent);color:var(--text)}.voice-recording{background:color-mix(in srgb,var(--bad) 14%,transparent);color:var(--bad);transition:background-color .16s ease}.voice-recording:hover{background:color-mix(in srgb,var(--bad) 22%,transparent)}.voice-recording-dot{background:var(--bad)}.voice-note{padding:6px 10px;border-radius:10px;border:1px solid color-mix(in srgb,var(--bad) 35%,transparent);background:var(--surface-solid);color:var(--bad);font-size:12px;line-height:1.4;box-shadow:var(--shadow-1)}@media (prefers-reduced-motion:reduce){.tutor-thinking-dots span{animation:none}.tutor-send:hover:not(:disabled){transform:none}}html[data-skin=classroom] .tutor-chip,html[data-skin=classroom] .tutor-new-chat,html[data-skin=classroom] .tutor-retry{border-radius:var(--skin-radius-btn)}html[data-skin=sketchbook] .tutor-bubble-ai,html[data-skin=sketchbook] .tutor-context,html[data-skin=sketchbook] .tutor-status,html[data-skin=sketchbook] .tutor-turn-note{border-width:var(--skin-line);border-radius:var(--skin-wobble-sm)}html[data-skin=sketchbook] .tutor-bubble-user{border-radius:var(--skin-wobble-sm)}html[data-skin=sketchbook] .tutor-chip,html[data-skin=sketchbook] .tutor-composer,html[data-skin=sketchbook] .tutor-new-chat,html[data-skin=sketchbook] .tutor-retry{border-width:var(--skin-line);border-radius:var(--skin-wobble-btn)}.inv-code-row{display:flex;align-items:center;gap:11px}.inv-code{flex:1;min-width:0;display:flex;border-radius:13px;border:1px dashed color-mix(in oklab,var(--brand) 34%,transparent);background:color-mix(in oklab,var(--brand) 8%,transparent);font-family:JetBrains Mono,ui-monospace,SFMono-Regular,Menlo,monospace;font-size:20px;letter-spacing:.24em;text-indent:.24em;-webkit-user-select:all;-moz-user-select:all;user-select:all}.inv-code,.inv-copy{height:52px;align-items:center;justify-content:center;font-weight:600;color:var(--text)}.inv-copy{display:inline-flex;gap:7px;padding:0 16px;border-radius:13px;border:1px solid var(--border);background:color-mix(in oklab,var(--text) 4%,transparent);font-size:12.5px;font-family:inherit;cursor:pointer}.inv-copy:hover{background:color-mix(in oklab,var(--text) 9%,transparent)}.inv-code:focus-visible,.inv-copy:focus-visible{outline:2px solid var(--brand);outline-offset:2px}.ob-scrim{position:fixed;inset:0;z-index:300;display:flex;align-items:center;justify-content:center;padding:24px;background:var(--modal-backdrop);backdrop-filter:blur(6px);-webkit-backdrop-filter:blur(6px)}.ob-panel{width:100%;max-width:28rem;max-height:calc(100dvh - 48px);overflow-y:auto;border-radius:.75rem;outline:none;animation:ob-rise .22s ease-out}.ob-panel.is-wide{max-width:34rem}.ob-panel>*{max-width:none}@keyframes ob-rise{0%{opacity:0;transform:translateY(10px) scale(.98)}to{opacity:1;transform:none}}@media (prefers-reduced-motion:reduce){.ob-panel{animation:none}}.ob-bar{display:flex;align-items:center;gap:8px;min-height:44px;margin:-8px -8px 12px}.ob-bar-label{flex:1;min-width:0;font-size:11px;font-weight:700;letter-spacing:.12em;text-transform:uppercase;color:var(--text-muted)}.ob-icon-btn{display:inline-flex;align-items:center;justify-content:center;width:44px;height:44px;flex-shrink:0;border-radius:999px;border:0;background:transparent;color:var(--text-muted);cursor:pointer;transition:background-color .15s,color .15s}.ob-icon-btn:hover{background:var(--surface-container-low);color:var(--text)}.ob-chip:focus-visible,.ob-icon-btn:focus-visible,.ob-option:focus-visible{outline:2px solid var(--brand);outline-offset:2px}.ob-screen{width:100%;max-width:28rem;margin:0 auto;padding:8px 0 32px;display:flex;flex-direction:column;gap:20px}.ob-screen>.ob-card{max-width:none}.ob-title{font-family:var(--font-headline,inherit);font-size:1.5rem;line-height:1.25;font-weight:700;color:var(--text)}.ob-sub{margin-top:4px;font-size:.875rem;line-height:1.5;color:var(--text-muted)}.ob-chips{display:flex;flex-wrap:wrap;gap:8px}.ob-chips.is-grid-4{display:grid;grid-template-columns:repeat(4,minmax(0,1fr))}.ob-chip{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-height:44px;padding:0 14px;border-radius:999px;border:1px solid var(--border);background:var(--surface-container-low);color:var(--text);font-size:.875rem;font-weight:600;cursor:pointer;transition:background-color .15s,border-color .15s,color .15s}.ob-chip:hover{border-color:color-mix(in oklab,var(--brand) 40%,var(--border))}.ob-chip[aria-checked=true]{border-color:var(--brand);background:color-mix(in oklab,var(--brand) 16%,transparent);color:var(--text)}.ob-chip-note{font-size:.75rem;font-weight:500;color:var(--text-muted)}.ob-option{display:flex;align-items:center;gap:16px;width:100%;min-height:64px;padding:16px;border-radius:.75rem;border:1px solid var(--border);background:var(--surface-container-low);color:var(--text);text-align:left;cursor:pointer;transition:transform .2s,box-shadow .2s,border-color .2s}.ob-option:hover{transform:scale(1.02)}.ob-option[aria-checked=true]{border-color:var(--brand)}.ob-note{display:flex;align-items:flex-start;gap:10px;padding:12px 14px;border-radius:.75rem;border:1px solid color-mix(in oklab,var(--brand) 30%,transparent);background:color-mix(in oklab,var(--brand) 10%,transparent);font-size:.8125rem;line-height:1.5;color:var(--text)}.ob-note>.material-symbols-outlined,.ob-note>svg{color:var(--brand);flex-shrink:0}