:root{--bg:#fbfbfd;--bg-elevated:rgba(0,0,0,0.04);--bg-glass:rgba(255,255,255,0.85);--text:rgba(0,0,0,0.88);--text-muted:rgba(0,0,0,0.6);--text-secondary:rgba(0,0,0,0.8);--text-tertiary:rgba(0,0,0,0.65);--border:rgba(0,0,0,0.08);--accent:#4370e8;--accent-soft:rgba(67,112,232,0.12);--accent-2:#05845e;--card-bg:var(--bg-glass);--danger:#d32f2f;--prereq-color:#f59e0b;--unlock-color:#059669;--radius-lg:20px;--radius-md:14px;--radius-sm:10px;--shadow:0 2px 20px rgba(0,0,0,0.06);--ease-out:cubic-bezier(0.23,1,0.32,1);--ease-in-out:cubic-bezier(0.77,0,0.175,1);--font:system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;--nav-h:56px;--safe-bottom:env(safe-area-inset-bottom,0px);--nav-bg:rgba(251,251,253,0.7);--overlay-bg:rgba(255,255,255,0.8);--btn-primary-text:#fff;--pre-bg:rgba(67,112,232,0.08);--pre-border:rgba(67,112,232,0.22);--blockquote-bg:rgba(67,112,232,0.06);--skeleton-shine:rgba(0,0,0,0.08);--bg-gradient-1:rgba(67,112,232,0.06);--bg-gradient-2:rgba(5,132,94,0.02)}:root.dark{--bg:#0b0c10;--bg-elevated:rgba(255,255,255,0.06);--bg-glass:rgba(255,255,255,0.08);--text:rgba(255,255,255,0.92);--text-muted:rgba(255,255,255,0.55);--text-secondary:rgba(255,255,255,0.88);--text-tertiary:rgba(255,255,255,0.78);--border:rgba(255,255,255,0.1);--accent:#7c9cff;--accent-soft:rgba(124,156,255,0.18);--accent-2:#8be9c2;--danger:#ff7b72;--prereq-color:#fbbf24;--unlock-color:#34d399;--shadow:0 24px 80px rgba(0,0,0,0.45);--nav-bg:rgba(11,12,16,0.55);--overlay-bg:rgba(11,12,16,0.6);--btn-primary-text:#0b0c10;--pre-bg:rgba(124,156,255,0.1);--pre-border:rgba(124,156,255,0.28);--blockquote-bg:rgba(124,156,255,0.09);--skeleton-shine:rgba(255,255,255,0.08);--bg-gradient-1:rgba(124,156,255,0.18);--bg-gradient-2:rgba(139,233,194,0.06)}*{box-sizing:border-box}body,html{margin:0;padding:0;min-height:100%;background:var(--bg);color:var(--text);font-family:var(--font);-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}body{background-image:radial-gradient(ellipse 80% 50% at 50% -20%,var(--bg-gradient-1),transparent),radial-gradient(ellipse 60% 40% at 100% 0,var(--bg-gradient-2),transparent);background-attachment:fixed}a{color:inherit;text-decoration:none}button,input,textarea{font:inherit;color:inherit}.shell{min-height:100dvh;flex-direction:column}.nav,.shell{display:flex}.nav{position:-webkit-sticky;position:sticky;top:0;z-index:40;height:var(--nav-h);align-items:center;justify-content:space-between;padding:env(safe-area-inset-top,0) 16px 0;background:var(--nav-bg);backdrop-filter:blur(20px) saturate(160%);-webkit-backdrop-filter:blur(20px) saturate(160%);border-bottom:1px solid var(--border)}.nav-brand{font-weight:650;letter-spacing:-.02em;font-size:1.05rem}.nav-links{display:flex;gap:6px;align-items:center}.nav-link{min-height:36px;padding:0 12px;border-radius:999px;display:inline-flex;align-items:center;color:var(--text-muted);transition:color .16s var(--ease-out),background .16s var(--ease-out)}.nav-link:hover{color:var(--text);background:var(--bg-elevated)}.nav-link[data-active=true]{color:var(--text);background:var(--accent-soft)}.lang-toggle{min-width:44px;min-height:36px;border:1px solid var(--border);background:transparent;border-radius:999px;cursor:pointer;color:var(--text-muted);transition:transform .14s var(--ease-out),background .16s var(--ease-out)}.lang-toggle:active{transform:scale(.97)}.sound-toggle{min-width:36px;min-height:36px;border:1px solid var(--border);background:transparent;border-radius:999px;cursor:pointer;color:var(--text-muted);font-size:1rem;transition:transform .14s var(--ease-out),background .16s var(--ease-out),opacity .16s var(--ease-out)}.sound-toggle:active{transform:scale(.97)}.sound-toggle-icon--off{opacity:.35}.theme-toggle{min-width:36px;min-height:36px;border:1px solid var(--border);background:transparent;border-radius:999px;cursor:pointer;color:var(--text-muted);font-size:.95rem;transition:transform .14s var(--ease-out),background .16s var(--ease-out);display:inline-flex;align-items:center;justify-content:center}.theme-toggle:active{transform:scale(.97)}.theme-toggle:hover{color:var(--text);background:var(--bg-elevated)}.map-legend{flex-direction:column;gap:3px 0}.main{flex:1 1;width:100%;max-width:720px;margin:0 auto;padding:32px 20px calc(40px + var(--safe-bottom))}.main-wide{max-width:1100px}.display{font-size:clamp(2rem,5vw,3.1rem);line-height:1.08;letter-spacing:-.025em;font-weight:650;margin:0 0 12px}.lede{margin:0 0 28px;color:var(--text-muted);font-size:1.05rem;line-height:1.55;max-width:36rem}.card{background:var(--bg-glass);border:1px solid var(--border);border-radius:var(--radius-lg);box-shadow:var(--shadow);backdrop-filter:blur(20px) saturate(160%);-webkit-backdrop-filter:blur(20px) saturate(160%)}.ask-card{padding:16px}.ask-textarea{width:100%;min-height:120px;resize:vertical;border:none;outline:none;background:transparent;color:var(--text);line-height:1.5;padding:8px 4px 12px}.ask-textarea::placeholder{color:color-mix(in srgb,var(--text) 35%,transparent)}.ask-textarea:focus{outline:none}.ask-actions{display:flex;align-items:center;justify-content:flex-end;gap:12px;flex-wrap:wrap;padding-top:4px}.btn-thinking{display:inline-flex;align-items:center;gap:10px;min-width:10.5rem;justify-content:center}.think-spinner{width:16px;height:16px;border-radius:50%;border:2px solid color-mix(in srgb,var(--btn-primary-text) 25%,transparent);border-top-color:var(--btn-primary-text);animation:spin .75s linear infinite;flex-shrink:0}.think-timer{font-variant-numeric:tabular-nums;font-feature-settings:"tnum";opacity:.85;min-width:2.4em}.think-spinner-on-dark{border-color:rgba(255,255,255,.2);border-top-color:var(--accent)}.answer-followups{display:flex;flex-wrap:wrap;gap:10px;margin-top:16px}.answer-followups-center{justify-content:center}.answer-block+.answer-block,.answer-deep{margin-top:22px;padding-top:18px;border-top:1px solid var(--border)}.answer-inline-wait{display:flex;align-items:center;gap:10px;margin-bottom:12px;font-size:.9rem;color:var(--text-muted)}@keyframes spin{to{transform:rotate(1turn)}}@media (prefers-reduced-motion:reduce){.think-spinner{animation:none;border-top-color:color-mix(in srgb,var(--btn-primary-text) 50%,transparent);opacity:.7}}.btn{min-height:44px;padding:0 18px;border-radius:999px;border:1px solid transparent;cursor:pointer;display:inline-flex;align-items:center;justify-content:center;gap:8px;transition:transform .14s var(--ease-out),background .16s var(--ease-out),opacity .16s var(--ease-out)}.btn:active{transform:scale(.97)}.btn:disabled{opacity:.55;cursor:not-allowed;transform:none}.btn-primary{background:var(--accent);color:var(--btn-primary-text);font-weight:600}.btn-primary:hover:not(:disabled){filter:brightness(1.05)}.btn-ghost{background:transparent;border-color:var(--border);color:var(--text)}.chips{display:flex;flex-wrap:wrap;gap:8px;margin-top:16px}.chip{min-height:36px;padding:0 12px;border-radius:999px;border:1px solid var(--border);background:var(--bg-elevated);color:var(--text-muted);cursor:pointer;transition:transform .14s var(--ease-out),color .16s var(--ease-out),border-color .16s var(--ease-out),background .16s var(--ease-out);display:inline-flex;align-items:center;gap:8px;max-width:100%;text-align:left}.chip:hover{color:var(--text);border-color:color-mix(in srgb,var(--text) 20%,transparent)}.chip:active{transform:scale(.97)}.chip-subject{border-color:color-mix(in srgb,var(--chip-accent,var(--accent)) 45%,transparent);background:color-mix(in srgb,var(--chip-accent,var(--accent)) 12%,transparent);color:var(--text-secondary)}.chip-subject:hover{border-color:color-mix(in srgb,var(--chip-accent,var(--accent)) 70%,transparent);background:color-mix(in srgb,var(--chip-accent,var(--accent)) 18%,transparent);color:var(--text)}.chip-subject .dot{flex-shrink:0}.chip-text{line-height:1.25;font-size:.9rem}.chips-topic-label{width:100%;font-size:.82rem;color:var(--text-muted);margin:0 0 4px 2px}.age-picker{margin:0 0 4px}.age-picker-label{font-size:.85rem;color:var(--text-muted);margin:0 0 8px}.age-options{display:flex;flex-wrap:wrap;gap:6px}.age-chip{min-width:40px;min-height:36px;padding:0 10px;border-radius:999px;border:1px solid var(--border);background:var(--bg-elevated);color:var(--text-muted);cursor:pointer;font-weight:600;font-size:.9rem;transition:transform .14s var(--ease-out),background .16s var(--ease-out),border-color .16s var(--ease-out),color .16s var(--ease-out)}.age-chip:hover{color:var(--text);border-color:color-mix(in srgb,var(--text) 22%,transparent)}.age-chip[data-active=true]{background:var(--accent-soft);border-color:color-mix(in srgb,var(--accent) 50%,transparent);color:var(--accent)}.age-chip:active{transform:scale(.97)}.answer{margin-top:28px;max-width:65ch;animation:rise .22s var(--ease-out) both}.answer-md{font-size:1.05rem;line-height:1.6;max-width:none}.answer-md h1,.answer-md h2,.answer-md h3{letter-spacing:-.02em;line-height:1.2;margin:1.4em 0 .5em}.answer-md h2{font-size:1.25rem}.answer-md p{margin:.7em 0;color:var(--text-secondary)}.answer-md ol,.answer-md ul{padding-left:1.2em;color:var(--text-secondary)}.answer-md code{font-size:.92em;background:var(--bg-elevated);padding:.1em .35em;border-radius:6px}.answer-md pre{margin:1.1em 0;padding:18px 20px;border-radius:var(--radius-md);border:1px solid var(--pre-border);background:var(--pre-bg);overflow-x:auto;-webkit-overflow-scrolling:touch;width:100%;box-sizing:border-box}.answer-md pre code{display:block;font-family:ui-monospace,SF Mono,Menlo,Consolas,monospace;font-size:1rem;line-height:1.65;background:transparent;padding:0;color:var(--text);white-space:pre}.answer-md blockquote{margin:.75em 0;padding:14px 16px 14px 18px;border-radius:var(--radius-md);border:1px solid var(--pre-border);border-left:4px solid var(--accent);background:var(--blockquote-bg);color:var(--text-secondary)}.answer-md blockquote p{margin:.35em 0}.answer-md blockquote strong{color:var(--text);font-size:1.02rem}.answer-md blockquote ol,.answer-md blockquote ul{margin:.4em 0 .2em;padding-left:1.15em}.answer-md blockquote+blockquote{margin-top:.65em}.answer-md .table-wrap{overflow-x:auto;-webkit-overflow-scrolling:touch;margin:1em 0;border-radius:var(--radius-md);border:1px solid var(--border)}.answer-md table{width:100%;border-collapse:collapse;font-size:.92rem;min-width:280px}.answer-md td,.answer-md th{padding:10px 12px;text-align:left;border-bottom:1px solid var(--border);vertical-align:top}.answer-md th{background:var(--pre-bg);color:var(--text);font-weight:600;white-space:nowrap}.answer-md tr:last-child td{border-bottom:none}.answer-md tbody tr:nth-child(2n) td{background:color-mix(in srgb,var(--text) 2%,transparent)}.answer-md .md-figure{margin:1.1em 0;max-width:100%}.answer-md .md-figure img,.answer-md img{display:block;max-width:min(100%,480px);width:100%;height:auto;border-radius:var(--radius-md);border:1px solid var(--border);background:rgba(0,0,0,.2)}.answer-md .md-figcaption{margin-top:8px;font-size:.8rem;color:var(--text-muted)}.answer-md a{color:var(--accent);text-decoration:underline;text-underline-offset:2px}.answer-sources{margin-top:20px;padding:14px 16px;border-radius:var(--radius-md);border:1px solid var(--border);background:var(--bg-elevated)}.answer-sources h3{margin:0 0 10px;font-size:.95rem;letter-spacing:-.01em}.answer-sources ol{margin:0;padding-left:1.2em;color:var(--text-muted);font-size:.9rem}.answer-sources li{margin-bottom:6px}.answer-sources a{color:var(--accent);word-break:break-word}.answer-image{margin:24px 0 0;width:100%;max-width:none;padding:12px;border-radius:var(--radius-md);border:1px solid var(--border);background:var(--bg-glass);animation:rise .28s var(--ease-out) both;text-align:center;box-sizing:border-box}.answer-image img{display:block;width:100%;max-width:100%;height:auto;margin:0 auto;border-radius:var(--radius-sm);background:rgba(0,0,0,.25);object-fit:contain}.answer-image-label{margin:10px 4px 0;font-size:.8rem;color:var(--text-muted);text-align:center}.answer-image-skeleton{width:100%;aspect-ratio:4/3;border-radius:var(--radius-sm);background:linear-gradient(90deg,color-mix(in srgb,var(--skeleton-shine) 50%,transparent) 0,var(--skeleton-shine) 50%,color-mix(in srgb,var(--skeleton-shine) 50%,transparent) 100%);background-size:200% 100%;animation:shimmer 1.4s ease-in-out infinite}@keyframes shimmer{0%{background-position:100% 0}to{background-position:-100% 0}}@media (prefers-reduced-motion:reduce){.answer-image-skeleton{animation:none;background:color-mix(in srgb,var(--text) 6%,transparent)}}.voice-explain{margin-top:16px}.voice-panel{justify-content:space-between;margin-top:8px;padding:14px 16px;border-radius:var(--radius-md,16px);border:1px solid var(--border);background:color-mix(in srgb,var(--surface,#1a1a1e) 92%,transparent);-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px)}.voice-panel,.voice-panel-main{display:flex;align-items:center;gap:12px}.voice-panel-main{min-width:0}.voice-panel-text{display:flex;flex-direction:column;gap:2px;min-width:0}.voice-panel-text strong{font-weight:560;font-size:.95rem;color:var(--text)}.voice-elapsed{font-size:.78rem;color:var(--text-muted);font-feature-settings:"tnum";font-variant-numeric:tabular-nums}.voice-pulse{width:12px;height:12px;border-radius:50%;background:color-mix(in srgb,var(--accent,#6ea8fe) 55%,transparent);flex-shrink:0}.voice-pulse-on{background:var(--accent,#6ea8fe);box-shadow:0 0 0 0 color-mix(in srgb,var(--accent,#6ea8fe) 55%,transparent);animation:voice-pulse 1.4s ease-out infinite}@keyframes voice-pulse{0%{box-shadow:0 0 0 0 color-mix(in srgb,var(--accent,#6ea8fe) 45%,transparent)}70%{box-shadow:0 0 0 12px transparent}to{box-shadow:0 0 0 0 transparent}}.voice-stop-btn{flex-shrink:0;padding-inline:14px}.voice-error{margin:10px 4px 0;font-size:.85rem;color:color-mix(in srgb,#f07178 85%,var(--text));text-align:center}@media (prefers-reduced-motion:reduce){.voice-pulse-on{animation:none}}.bridge{margin-top:32px}.bridge h2{font-size:1.15rem;letter-spacing:-.02em;margin:0 0 14px}.bridge-list{display:grid;grid-gap:10px;gap:10px}.bridge-card{display:block;padding:14px 16px;border-radius:var(--radius-md);border:1px solid var(--border);background:var(--bg-elevated);transition:transform .16s var(--ease-out),border-color .16s var(--ease-out),background .16s var(--ease-out);animation:rise .22s var(--ease-out) both}.bridge-card:hover{border-color:color-mix(in srgb,var(--text) 18%,transparent);background:color-mix(in srgb,var(--text) 6%,transparent)}.bridge-card:active{transform:scale(.99)}.bridge-card-prereq{border-left:3px solid var(--prereq-color)}.bridge-card-unlock{border-left:3px solid var(--unlock-color)}.bridge-top{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-bottom:6px}.bridge-name{font-weight:600;letter-spacing:-.01em}.bridge-meta{font-size:.85rem;color:var(--text-muted);margin-bottom:6px}.bridge-reason{font-size:.95rem;color:var(--text-tertiary);line-height:1.45}.badge{font-size:.72rem;font-weight:600;letter-spacing:.02em;text-transform:uppercase;padding:4px 8px;border-radius:999px;background:var(--accent-soft);color:var(--accent);white-space:nowrap}.badge-prereq{background:color-mix(in srgb,var(--prereq-color) 22%,transparent);color:var(--prereq-color)}.badge-related{background:var(--bg-elevated);color:var(--text-muted)}.dot{width:8px;height:8px;border-radius:50%;display:inline-block;margin-right:6px}.error-banner{margin-top:16px;padding:12px 14px;border-radius:var(--radius-md);border:1px solid color-mix(in srgb,var(--danger) 35%,transparent);background:color-mix(in srgb,var(--danger) 10%,transparent);color:var(--danger);animation:rise .2s var(--ease-out) both}.footer{margin-top:48px;padding-top:16px;border-top:1px solid var(--border);font-size:.78rem;color:var(--text-muted);line-height:1.45}.footer a{text-decoration:underline;text-underline-offset:2px}.footer-attribution{margin-top:24px;padding:12px 0;text-align:center;border-top:1px solid var(--border)}.attribution-text{font-size:.7rem;opacity:.35;color:var(--text-muted)}.attribution-text a{color:inherit}.tree-search{width:100%;min-height:44px;border-radius:var(--radius-md);border:1px solid var(--border);background:var(--bg-glass);padding:0 14px;margin-bottom:20px;outline:none;transition:border-color .16s var(--ease-out)}.tree-search:focus{border-color:rgba(124,156,255,.5)}.subject-block{margin-bottom:18px;border:1px solid var(--border);border-radius:var(--radius-md);overflow:hidden;background:var(--bg-elevated)}.subject-head{width:100%;text-align:left;background:transparent;border:none;color:var(--text);padding:14px 16px;cursor:pointer;font-weight:600;letter-spacing:-.01em;display:flex;justify-content:space-between;align-items:center}.subject-head:active{transform:none}.domain{padding:0 12px 12px}.domain-title{font-size:.85rem;color:var(--text-muted);margin:8px 4px;text-transform:uppercase;letter-spacing:.04em}.topic-row{display:block;padding:10px 12px;border-radius:10px;color:var(--text);transition:background .14s var(--ease-out)}.topic-row:hover{background:color-mix(in srgb,var(--text) 6%,transparent)}.topic-age{font-size:.8rem;color:var(--text-muted)}.topic-hero{padding:22px;margin-bottom:20px}.topic-hero h1{margin:8px 0 10px;font-size:clamp(1.6rem,4vw,2.2rem);letter-spacing:-.025em;line-height:1.15}.topic-desc{color:var(--text-secondary);line-height:1.55;margin:0}.section-title{font-size:.9rem;text-transform:uppercase;letter-spacing:.05em;color:var(--text-muted);margin:22px 0 10px}.topic-section{margin:18px 0;padding:14px 14px 16px;border-radius:var(--radius-md);border:1px solid var(--border)}.topic-section-prereq{background:rgba(251,191,36,.07);border-color:rgba(251,191,36,.22)}.topic-section-unlock{background:rgba(52,211,153,.06);border-color:rgba(52,211,153,.2)}.topic-section .section-title{margin:0 0 12px}.section-title-prereq{color:var(--prereq-color)}.section-title-unlock{color:var(--unlock-color)}.topic-section .bridge-list{margin:0}.map-page{max-width:none;padding:0;height:calc(100dvh - var(--nav-h));position:relative}.map-canvas{width:100%;height:100%;display:block;touch-action:none;cursor:-webkit-grab;cursor:grab}.map-canvas:active{cursor:-webkit-grabbing;cursor:grabbing}.map-panel{position:absolute;left:16px;right:16px;bottom:calc(80px + var(--safe-bottom));max-width:420px;padding:16px;animation:rise .22s var(--ease-out) both}.map-hint{top:12px;left:50%;transform:translateX(-50%);font-size:.8rem;color:var(--text-muted);-webkit-backdrop-filter:blur(12px);padding:6px 12px;border-radius:999px;border:1px solid var(--border);white-space:nowrap}.map-hint,.map-legend{position:absolute;background:var(--overlay-bg);backdrop-filter:blur(12px)}.map-legend{top:calc(8px + env(safe-area-inset-top, 0px));left:16px;display:flex;flex-wrap:wrap;gap:4px 8px;padding:8px 12px;-webkit-backdrop-filter:blur(12px);border-radius:var(--radius-sm);border:1px solid var(--border);max-width:260px;z-index:1}.map-legend-item{display:flex;align-items:center;font-size:.7rem;color:var(--text-muted);white-space:nowrap}@keyframes rise{0%{opacity:0;transform:translateY(8px) scale(.98)}to{opacity:1;transform:translateY(0) scale(1)}}@media (prefers-reduced-motion:reduce){*,:after,:before{animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important}@keyframes rise{0%{opacity:0}to{opacity:1}}}.explore-section{margin-top:48px;padding-top:24px}.explore-title{font-size:1.15rem;letter-spacing:-.02em;margin:0 0 16px}.explore-map-container{height:420px;border-radius:var(--radius-md);overflow:hidden;border:1px solid var(--border);position:relative;margin-bottom:20px}.explore-map-inner{position:relative}.explore-map-inner,.explore-map-inner .map-canvas{width:100%;height:100%}.explore-legend{display:flex;flex-wrap:wrap;gap:8px 14px;margin-bottom:16px;padding:8px 12px;background:var(--bg-elevated);border-radius:var(--radius-sm);border:1px solid var(--border)}.explore-legend-item{display:flex;align-items:center;font-size:.75rem;color:var(--text-muted);white-space:nowrap}@media (max-width:600px){.explore-map-container{height:320px}}@media (hover:none){.bridge-card:hover,.chip:hover,.nav-link:hover,.topic-row:hover{background:inherit}}