/* Google Material palette; spatial layouts follow shared teaching-quality guidance. */
*{box-sizing:border-box}html{scrollbar-gutter:stable;scroll-behavior:smooth}body{margin:0;background:#f8f9fa;color:#202124;font-family:-apple-system,BlinkMacSystemFont,'Noto Sans TC',Arial,sans-serif;line-height:1.7}.container{max-width:1100px;margin:auto;padding:28px 24px}header{padding:12px 12px 24px}header h1{font-size:30px;line-height:1.4;font-weight:650;margin:8px 0 14px}header p{max-width:780px;margin:10px 0;color:#5f6368}.dt-eyebrow{font-size:13px;letter-spacing:.09em;color:#1967d2}.tabs.tabs{position:sticky;top:0;z-index:30;display:flex;flex-wrap:nowrap;overflow:auto;gap:6px;background:#f8f9fa;margin:0;border-bottom:1px solid #dadce0;scrollbar-width:thin}.tabs .tab.tab{flex-shrink:0;font-size:15px;min-height:54px;padding:12px 15px;color:#5f6368;border:0;border-bottom:3px solid transparent;border-radius:0;box-shadow:none;background:transparent;cursor:pointer}.tabs .tab.active{color:#174ea6;border-bottom-color:#1967d2}.scene{display:none}.scene.active{display:block}.dt-unit{background:white;padding:28px;margin:0 0 18px;border:0;border-bottom:1px solid #dadce0;scroll-margin-top:130px}.dt-unit h2{font-size:25px;line-height:1.45;margin:0 0 14px;font-weight:650}.dt-unit h3{font-size:20px;line-height:1.5;margin:14px 0 10px}.dt-unit p,.dt-unit li,.dt-unit dd{font-size:16px;line-height:1.8}.dt-unit p{margin:10px 0}.dt-unit .dt-intro{color:#5f6368;margin-bottom:20px}.dt-small,.dt-unit .dt-small{font-size:14px;color:#5f6368}.dt-work{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:28px;align-items:start;margin:18px 0}.dt-unit figure{margin:0;min-width:0}.dt-unit figcaption{font-size:14px;color:#5f6368;line-height:1.65;margin:0 0 10px}.dt-unit svg{width:100%;height:auto;display:block;background:#f8f9fa;border:0;border-radius:5px;font-family:Arial,'Noto Sans TC',sans-serif}.dt-unit svg text{font-size:14px;fill:#3c4043}.dt-unit svg [hidden]{display:none!important}.dt-controls{display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin:14px 0}.dt-unit button,.dt-unit select,.dt-jumps button,.dt-jumps select{font:inherit;min-height:44px;border:1px solid #dadce0;background:white;color:#3c4043;border-radius:6px;padding:9px 12px;cursor:pointer;box-shadow:none}.dt-unit button[aria-pressed=true]{color:#174ea6;background:#e8f0fe;border-color:#e8f0fe}.dt-unit button:hover,.dt-jumps button:hover{background:#f1f3f4}button:focus-visible,a:focus-visible,select:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid #1967d2;outline-offset:3px}.dt-unit label{font-size:15px;display:flex;gap:8px;align-items:center;color:#3c4043}.dt-unit input[type=checkbox]{width:20px;height:20px;accent-color:#1967d2}.dt-unit label.dt-slider{display:block;flex:1;min-width:220px}.dt-slider input{width:100%;display:block;accent-color:#1967d2;min-height:34px;margin:5px 0}.dt-slider output{color:#174ea6;font-variant-numeric:tabular-nums}.dt-columns{display:grid;grid-template-columns:1fr 1fr;gap:28px}.dt-note{background:#f1f3f4;padding:14px 16px;border:0;border-radius:5px}.dt-metrics{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px;margin:18px 0}.dt-metric{border-top:1px solid #dadce0;padding-top:10px}.dt-metric span{font-size:13px;color:#5f6368;display:block}.dt-metric strong{font-size:25px;font-weight:550;line-height:1.4;display:block;font-variant-numeric:tabular-nums}.dt-unit details{padding:0;border:0}.dt-unit summary{font-size:16px;color:#174ea6;cursor:pointer;min-height:44px;padding:8px 0}.dt-unit details a{display:block;color:#174ea6;text-decoration:none;font-size:15px;padding:9px 0;overflow-wrap:anywhere}.dt-unit a:hover{text-decoration:underline}.dt-next{display:inline-block;text-decoration:none;color:#174ea6;padding:12px 0}.dt-unit ul,.dt-unit ol{padding-left:23px}.dt-unit li{margin:6px 0}.dt-unit dt{font-weight:650;margin-top:18px}.dt-unit dd{margin:5px 0}.dt-equation{overflow-wrap:anywhere;font-variant-numeric:tabular-nums}.dt-kicker{font-size:14px;color:#1967d2;font-weight:650;letter-spacing:.03em}.dt-jumps{position:sticky;top:54px;z-index:20;background:#fff;border-bottom:1px solid #dadce0;padding:7px 12px;margin-bottom:18px}.dt-jump-links{display:flex;gap:18px;flex-wrap:wrap}.dt-jumps a{padding:7px 0;text-decoration:none;color:#5f6368;font-size:14px}.dt-jumps a[aria-current=true]{color:#174ea6;font-weight:650}.dt-mobile-nav{display:none}.dt-jumps select{min-width:0;flex:1;text-align:center}.dt-jumps button:disabled{opacity:.35;cursor:default}footer{padding:20px 12px;font-size:14px;color:#5f6368}footer a{display:inline-block;margin-right:18px;color:#174ea6;text-decoration:none}
@media(max-width:650px){.dt-unit svg text{font-size:16px}.dt-metric strong{overflow-wrap:anywhere}.container{padding:18px 12px}header{padding:5px 5px 18px}header h1{font-size:26px}.dt-unit{padding:21px 14px}.dt-unit h2{font-size:22px}.dt-unit h3{font-size:19px}.dt-work,.dt-columns{grid-template-columns:1fr;gap:17px}.dt-unit button,.dt-unit select{font-size:14px;padding:8px 10px}.dt-controls{gap:7px}.dt-metrics{gap:9px}.dt-metric strong{font-size:21px}.dt-jump-links{display:none}.dt-mobile-nav{display:flex;gap:8px}.dt-jumps{padding:7px}.tabs .tab.tab{font-size:14px}.dt-unit{scroll-margin-top:137px}.dt-unit label.dt-slider{min-width:240px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{animation:none!important;transition:none!important}}