@import url('https://fonts.googleapis.com/css2?family=DM+Mono:wght@400;500&family=Noto+Sans+TC:wght@400;500;600;700;800&display=swap');
:root{--bg:#f5f3eb;--ink:#182b33;--muted:#65767a;--line:#d9dfd9;--card:#fffefa;--a:#2369b6;--b:#168673;--result:#df6549;--grid:#e8eeea;--axis:#8a9a9b}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--bg);color:var(--ink);font-family:'Noto Sans TC',sans-serif}button,input{font:inherit}button{cursor:pointer}button:focus-visible,a:focus-visible,input:focus-visible{outline:3px solid #edae4b;outline-offset:3px}a{color:inherit}.site-shell{max-width:1460px;margin:auto;padding:24px clamp(18px,4vw,60px) 48px}.site-header{display:flex;align-items:center;justify-content:space-between;gap:16px;padding-bottom:22px;border-bottom:1px solid var(--line)}.back-link{text-decoration:none;font-size:14px;font-weight:700}.back-link:hover{text-decoration:underline}.eyebrow,.section-kicker,.result-label,.graph-heading,.graph-footer,.concept-strip>span{font-family:'DM Mono','Noto Sans TC',monospace;letter-spacing:.08em}.eyebrow{color:var(--muted);font-size:12px}.intro{display:flex;justify-content:space-between;align-items:end;gap:32px;padding:36px 0 30px}.section-kicker{font-size:11px;color:var(--b);font-weight:500;margin:0 0 10px}.intro h1{font-size:clamp(36px,5vw,64px);letter-spacing:-.06em;line-height:1.2;margin:0;font-weight:800}.title-mark{color:var(--result);font-family:'DM Mono',monospace;font-size:.8em;margin-left:12px}.intro-copy{font-size:clamp(14px,1.6vw,17px);color:var(--muted);margin:14px 0 0}.intro-note{width:170px;min-height:92px;background:#dcece7;display:flex;flex-direction:column;justify-content:center;padding:16px 22px;border-radius:90px 90px 12px 12px;transform:rotate(5deg);font-size:15px;color:#28685d}.intro-note strong{font-size:19px}.unit-nav{display:flex;gap:8px;margin-bottom:18px;overflow-x:auto;padding:2px 2px 8px}.unit-tab{flex:1;min-width:170px;text-align:left;background:transparent;border:1px solid var(--line);color:var(--muted);padding:13px 18px;border-radius:10px;font-weight:700;white-space:nowrap;transition:background .2s,transform .2s,color .2s}.unit-tab span{font-family:'DM Mono',monospace;font-size:12px;margin-right:12px}.unit-tab:hover{transform:translateY(-2px);background:#fff}.unit-tab.active{background:var(--ink);border-color:var(--ink);color:white}.unit-tab.active span{color:#aee4d3}.workspace{display:grid;grid-template-columns:minmax(300px,360px) minmax(0,1fr);gap:18px}.lesson-card,.graph-card{background:var(--card);border:1px solid var(--line);border-radius:16px;box-shadow:0 10px 32px #18384309}.lesson-card{padding:26px;display:flex;flex-direction:column;gap:24px}.lesson-heading h2{font-size:27px;letter-spacing:-.04em;margin:0 0 10px}.lesson-heading>p:last-child{color:var(--muted);font-size:14px;line-height:1.75;margin:0}.unit-controls{border-top:1px solid var(--line);padding-top:20px}.unit-controls[hidden]{display:none}.control-caption{font-size:13px;font-weight:700;margin:0 0 10px}.color-a{color:var(--a)}.color-b{color:var(--b)}.coordinate-fields{display:flex;gap:10px}.coordinate-fields label{flex:1;min-width:0;display:flex;align-items:center;justify-content:space-between;gap:8px;border:1px solid var(--line);border-radius:9px;padding:5px 10px;font-family:'DM Mono',monospace;color:var(--muted);background:white}.coordinate-fields input{width:100%;min-width:0;max-width:70px;border:0;text-align:right;font-family:'DM Mono',monospace;font-size:17px;font-weight:500;color:var(--ink);background:transparent;padding:6px 0}.preset-row{display:flex;flex-wrap:wrap;gap:7px;margin-top:12px}.preset{background:#f0f5f1;border:1px solid #dce8df;color:#385c58;border-radius:7px;padding:7px 10px;font-size:12px;font-weight:700}.preset:hover{background:#e2eee8}.segmented{display:flex;padding:4px;gap:4px;background:#edf1ed;border-radius:9px;margin-bottom:19px}.mode-button{flex:1;border:0;border-radius:6px;background:transparent;padding:9px;font-family:'DM Mono',monospace;color:var(--muted)}.mode-button.active{background:white;color:var(--ink);box-shadow:0 1px 5px #00000016}.vector-fields{display:grid;gap:16px}.mini-hint{font-size:12px;line-height:1.6;color:var(--muted);margin:14px 0 0}.result-card{background:#eef5f3;border-radius:10px;padding:17px 18px}.result-label{font-size:11px;font-weight:500;color:#437469;margin:0 0 12px}.result-label span{float:right;color:#94aaa3}#values{font-family:'DM Mono','Noto Sans TC',monospace;font-size:14px;line-height:1.85}#values strong{font-size:18px;color:var(--ink)}#values .math-line{display:block}.insight-card{border-left:3px solid var(--result);padding:1px 0 1px 14px}.insight-card .result-label{color:var(--result);margin-bottom:7px}.insight-card p:last-child{font-size:13px;line-height:1.7;margin:0;color:#4f5f60}.graph-card{min-width:0;display:flex;flex-direction:column;padding:18px}.graph-heading,.graph-footer{display:flex;justify-content:space-between;align-items:center;gap:12px;font-size:11px;color:var(--muted)}.graph-heading{padding:0 4px 15px}.graph-heading>div{color:var(--ink);font-weight:500}.graph-status{display:inline-block;width:8px;height:8px;border-radius:50%;background:var(--b);margin-right:6px}.canvas-wrap{height:clamp(380px,48vw,590px);border:1px solid var(--line);border-radius:10px;overflow:hidden;background:white}#gridCanvas{display:block;width:100%;height:100%;touch-action:none;cursor:crosshair}.graph-footer{padding:14px 4px 0;line-height:1.5}.legend{display:flex;gap:13px;flex-wrap:wrap}.legend span{white-space:nowrap}.dot{display:inline-block;width:8px;height:8px;border-radius:50%;margin-right:5px}.dot.a{background:var(--a)}.dot.b{background:var(--b)}.dot.result{background:var(--result)}.concept-strip{display:flex;gap:24px;align-items:center;border-top:1px solid var(--line);margin-top:28px;padding-top:20px}.concept-strip>span{font-size:11px;color:var(--b);white-space:nowrap}.concept-strip p{font-size:13px;color:var(--muted);margin:0}.concept-strip b{padding:0 10px;color:var(--result)}
@media(max-width:900px){.workspace{grid-template-columns:1fr}.lesson-card{gap:18px}.graph-card{order:-1}.canvas-wrap{height:470px}.intro-note{display:none}}@media(max-width:600px){.site-shell{padding:16px 14px 34px}.site-header{padding-bottom:15px}.eyebrow{font-size:10px}.intro{padding:26px 4px 22px}.intro-copy{line-height:1.6}.unit-tab{min-width:145px;padding:12px}.workspace{gap:12px}.graph-card{padding:10px}.canvas-wrap{height:370px}.graph-heading{padding:4px 4px 10px}.graph-footer{align-items:flex-start;flex-direction:column;padding:10px 4px 2px}.lesson-card{padding:20px}.concept-strip{align-items:flex-start;gap:8px;flex-direction:column}.concept-strip b{padding:0 4px}}@media(prefers-reduced-motion:reduce){*,*:before,*:after{scroll-behavior:auto!important;transition:none!important}}