:root{color-scheme:light;--background:#fff;--foreground:#202124;--red:#bd2833;--border:#e3e3e6;--muted:#f1f2f4;--muted-foreground:#666;--primary:#252529;--primary-foreground:#fff;--accent:#f4eeee;--accent-foreground:#9b2028;--font-size-base:16px;}
*{box-sizing:border-box}body{margin:0;background:#f6f6f7;color:var(--foreground);font-family:"Source Han Sans SC","Noto Sans CJK SC","Noto Sans SC","Microsoft YaHei",sans-serif;font-size:16px;line-height:1.65}button,input,select{font:inherit}button,select,input[type=range],input[type=checkbox]{cursor:pointer}button:focus-visible,select:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid #bc5361;outline-offset:3px}button:disabled{cursor:default;opacity:.4}button{touch-action:manipulation}header{background:#fff;border-bottom:1px solid var(--border)}.topbar{max-width:1120px;margin:auto;padding:19px 28px;display:flex;align-items:center;justify-content:space-between;gap:12px}.brand{display:flex;gap:12px;align-items:center}.brand-mark{width:36px;height:36px;background:#bd2833;border-radius:9px;color:#fff;display:grid;place-items:center;font-size:17px;font-weight:600}.brand-name{font-weight:600;font-size:16px}.brand-sub{font-size:12px;color:#777}.top-note{font-size:13px;color:#777}main{max-width:1120px;padding:34px 28px 44px;margin:auto}.intro{margin-bottom:26px}.eyebrow{color:#a62b35;font-size:13px;letter-spacing:.05em}h1{font-size:32px;line-height:1.4;margin:7px 0 9px;font-weight:600}h2{font-size:20px;line-height:1.4;margin:3px 0;font-weight:600}.intro p{color:#64646a;margin:0;max-width:760px}.lesson{background:#fff;border:1px solid var(--border);border-radius:16px;padding:24px;box-shadow:0 5px 22px #22222204}.lesson-heading{display:flex;align-items:center;justify-content:space-between;gap:16px;margin-bottom:22px}.lesson-tag{font-size:12px;color:#666;white-space:nowrap;background:#f4f4f5;padding:5px 10px;border-radius:20px}.viz-controls,.viz-row{display:flex;align-items:center;gap:10px;flex-wrap:wrap}.viz-controls{justify-content:space-between;margin-bottom:15px;gap:14px}.form-label{display:flex;flex-direction:column;gap:6px;font-size:13px;color:#555;max-width:100%}.form-select{background:#fff;color:#252529;border:1px solid #d6d6da;border-radius:8px;padding:9px 34px 9px 12px;font-size:15px;max-width:100%;min-height:44px}.form-check{display:flex;align-items:center;gap:7px;min-height:44px;font-size:14px}.form-check-input{width:17px;height:17px;accent-color:#bd2833}.btn{background:#fff;color:#333;border:1px solid #d9d9dd;border-radius:8px;padding:8px 14px;min-height:43px;font-size:14px;transition:background .15s}.btn:hover:not(:disabled){background:#f4f4f5}.btn-primary{background:#27272b;border-color:#27272b;color:#fff}.btn-primary:hover:not(:disabled){background:#414146}.btn[aria-pressed=true]{background:#27272b;color:#fff;border-color:#27272b}.form-range{width:100%;accent-color:#bd2833;margin:15px 0 6px;height:24px}.tabular-nums{font-variant-numeric:tabular-nums}.text-small{font-size:13px;color:#717176}#wb-count{font-size:13px;color:#737379;margin-left:4px}#wb-status{background:#f8f5f5;padding:10px 13px;border-left:3px solid #bc2935;border-radius:0 6px 6px 0;font-size:14px}#wb-drawing{margin-top:8px}#wb-legend{border-top:1px solid #eee;padding-top:13px;margin-top:12px}#wb-paths .btn{font-size:13px}.lower{display:grid;grid-template-columns:1.1fr 1fr;gap:18px;margin-top:20px}.info{background:#fff;border:1px solid var(--border);border-radius:12px;padding:19px 21px}.info h2{font-size:17px;margin:0 0 12px}.info p{font-size:14px;color:#62626a;margin:6px 0 15px}.info summary{cursor:pointer;font-size:15px;font-weight:500;min-height:32px}table{width:100%;border-collapse:collapse;font-size:14px;margin-top:10px}th,td{text-align:center;padding:7px 5px;border-bottom:1px solid #eee}th{font-weight:500;color:#65656c;background:#fafafa}.rule{margin:11px 0 0;padding:10px 0;border-bottom:1px solid #eee}.rule:last-child{border:0}.rule b{font-size:14px;font-weight:500}.rule div{font-size:14px;color:#65656c;margin-top:2px}.tips{margin:15px 0 0;font-size:13px;color:#777}footer{text-align:center;padding:0 20px 24px;color:#8a8a90;font-size:12px}[hidden]{display:none!important}@media(max-width:650px){.topbar{padding:15px 17px}.top-note{display:none}main{padding:24px 12px 30px}h1{font-size:26px}.intro{padding:0 5px}.intro p{font-size:14px}.lesson{padding:16px 11px;border-radius:12px}.lesson-heading{align-items:flex-start;margin-bottom:16px}.lesson-tag{display:none}h2{font-size:18px}.lower{grid-template-columns:1fr;gap:12px}.info{padding:17px}#wb-status{font-size:13px}.form-select{font-size:16px}.btn{min-height:44px}.brand-sub{font-size:11px}.text-small{font-size:12px}}

 #cpm-whiteboard{font-family:"Source Han Sans SC","Noto Sans CJK SC","Noto Sans SC",sans-serif;color:var(--foreground);}
 #cpm-whiteboard #wb-status{margin:12px 0;min-height:2em;}
 #cpm-whiteboard #wb-drawing{width:100%;}
 #cpm-whiteboard .wb-svg{display:block;width:100%;overflow:visible;}
 #cpm-whiteboard .wb-svg text{font-size:12px;font-weight:400;fill:var(--foreground);}
 #cpm-whiteboard .wb-svg .wb-note{fill:var(--red);}
 #cpm-whiteboard .wb-svg .wb-guide{fill:var(--muted-foreground);}
 #cpm-whiteboard .wb-svg .wb-edge{fill:none;stroke:var(--foreground);stroke-width:1.2;}
 #cpm-whiteboard .wb-svg .wb-active-edge{stroke:var(--red);stroke-width:2;}
 #cpm-whiteboard .wb-svg .wb-tracer{stroke:var(--red);stroke-width:2.5;stroke-dasharray:12 88;animation:wb-trace 900ms ease-out 1;}
 @keyframes wb-trace{from{stroke-dashoffset:100}to{stroke-dashoffset:0}}
 @media(prefers-reduced-motion:reduce){#cpm-whiteboard .wb-svg .wb-tracer{animation:none;}}
.voice-toolbar{display:flex;gap:12px;align-items:flex-end;flex-wrap:wrap;border-top:1px solid #eee;border-bottom:1px solid #eee;padding:14px 0;margin-bottom:14px}.voice-toolbar .form-label{min-width:105px}.voice-toolbar .form-check{margin:0 2px}.narration-panel{margin-top:17px;padding:15px 17px;background:#f8f5f5;border-radius:9px}.narration-heading{display:flex;justify-content:space-between;flex-wrap:wrap;gap:7px;font-size:13px;color:#9e2a34}.narration-heading span:first-child{font-weight:600}.narration-panel p{font-size:15px;line-height:1.85;margin:8px 0 0;color:#45454a}#voice-state{color:#76767b;font-size:12px}#voice-audio{display:none}@media(max-width:650px){.voice-toolbar{gap:9px}.voice-toolbar .form-select{padding-right:25px}.voice-toolbar .form-label{min-width:90px}.narration-panel{padding:13px}.narration-panel p{font-size:14px}}

.intro{display:grid;grid-template-columns:1fr auto;align-items:center;gap:24px}.intro h1{font-size:31px}.intro-copy p{max-width:740px}.case-badges{display:flex;gap:7px;flex-wrap:wrap;margin-top:16px}.case-badges span{font-size:12px;padding:4px 10px;border:1px solid #ddd;border-radius:20px;background:#fff}.library-art{width:138px;height:112px;opacity:.8}.chapter-nav{display:flex;gap:8px;overflow:auto;margin:0 0 20px;padding:2px 0 7px}.chapter-nav .btn{flex:0 0 auto}.chapter-nav .btn[aria-current=true]{border-color:#bd2833;color:#a8212c;background:#fff4f4}.case-question{font-size:14px;margin:0 0 17px;color:#666;border-bottom:1px solid #eee;padding-bottom:15px}.case-condition{display:flex;gap:9px;align-items:flex-start;font-size:13px;color:#8f2630;background:#fbf2f2;padding:10px 12px;border-radius:6px;margin-bottom:12px}.case-condition b{white-space:nowrap}.case-board{padding:6px 0 12px;min-height:330px}.case-board h3{font-size:23px;line-height:1.5;margin:5px 0 18px}.case-note{border:1px solid #e7e7e8;border-radius:10px;padding:15px 17px;margin:13px 0;background:#fff}.case-note b{font-size:15px}.case-note p{font-size:15px;margin:7px 0 0;color:#626269;line-height:1.9}.case-formula{font-size:23px;line-height:1.95;background:#faf5f5;border-left:3px solid #bd2833;padding:15px 19px;border-radius:0 8px 8px 0;margin:14px 0;overflow-wrap:anywhere;font-variant-numeric:tabular-nums}.case-scene{display:flex;align-items:center;gap:20px;background:#f7f7f8;padding:24px;border-radius:12px;margin:8px 0 20px}.case-scene h3{margin:3px 0 8px}.case-scene p{margin:0;font-size:14px;color:#666}.scene-icon{border:2px solid #444;border-radius:9px;width:62px;height:76px;display:grid;place-items:center;font-size:28px;flex-shrink:0;box-shadow:-5px 5px 0 #ddd}.case-metrics{display:grid;grid-template-columns:repeat(3,1fr);gap:11px;margin:18px 0}.case-metrics:has(>.case-metric:nth-child(2):last-child){grid-template-columns:repeat(2,1fr)}.case-metrics.four{grid-template-columns:repeat(2,1fr)}.case-metric{border:1px solid #e3e3e6;padding:17px 15px;border-radius:10px;display:flex;flex-direction:column;gap:5px;background:#fff}.case-metric span,.case-metric small{font-size:13px;color:#74747a}.case-metric strong{font-size:25px;font-weight:600;line-height:1.5;overflow-wrap:anywhere}.case-table-wrap{overflow:auto;width:100%;border:1px solid #eee;border-radius:8px;margin:15px 0}.case-table-wrap table{margin:0;min-width:400px}.case-table-wrap th,.case-table-wrap td{padding:10px}.case-table-wrap tfoot{font-weight:600;background:#f7f7f8}.case-highlight{background:#fff1f1}.case-source{font-size:12px;color:#777}.case-experiment{margin-top:24px;padding:20px;border:1px solid #d6d6da;border-radius:12px;background:#fafafa}.case-experiment h4{font-size:17px;margin:0 0 7px}.case-experiment>p{font-size:13px;color:#6b6b71;margin:0 0 12px}.crash-options{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;margin:16px 0}.crash-option{display:flex;align-items:center;gap:6px;background:white;border:1px solid #ddd;padding:10px 8px;border-radius:7px;cursor:pointer;font-size:14px;min-height:45px}.crash-option input{accent-color:#bd2833;width:17px;height:17px}.crash-option small{color:#777;font-size:11px}.crash-options .disabled{opacity:.55;cursor:default}.crash-result{font-size:15px;margin-top:12px}.crash-result .case-metric strong{color:#a6232e}.case-label{font-size:12px;color:#777}.case-pass{border-left:3px solid #bd2833;padding:9px 13px;background:#fff;font-size:14px}.next-chapter{margin-top:20px}.full-table table{min-width:530px}.source-details summary{font-weight:600}.source-details p{margin-bottom:12px}.full-question{font-size:14px;padding:9px 0;border-bottom:1px solid #eee}.lower .info p{line-height:1.9}
@media(max-width:650px){.intro{grid-template-columns:1fr;gap:0}.library-art{display:none}.intro h1{font-size:27px}.chapter-nav{margin-bottom:14px}.case-board h3{font-size:20px}.case-scene{padding:17px;gap:15px}.scene-icon{width:45px;height:61px;font-size:23px}.case-note{padding:13px}.case-note p{font-size:14px}.case-formula{font-size:18px;padding:12px 13px}.case-metrics{grid-template-columns:1fr;gap:8px}.case-metrics.four{grid-template-columns:1fr 1fr}.case-metric{padding:12px}.case-metric strong{font-size:21px}.case-metric small{font-size:12px}.case-experiment{padding:13px}.crash-options{grid-template-columns:1fr 1fr}.case-question{font-size:13px}.case-condition{font-size:12px;gap:7px}.case-condition b{white-space:normal;flex-shrink:0}.case-table-wrap th,.case-table-wrap td{padding:8px}.case-badges span{font-size:11px}.case-source{font-size:11px}}