:root{--ink:#163147;--muted:#526576;--blue:#136dc5;--purple:#7138b9;--green:#087c58;--orange:#b9510a;--red:#bb2355;font-family:'Microsoft JhengHei','Noto Sans TC',sans-serif;color:var(--ink);background:#eef8fc}*{box-sizing:border-box}body{margin:0;font-size:18px}button,a,input,select{font:inherit}button,.button{border:1px solid #aac8dc;border-radius:12px;background:linear-gradient(#fff,#dceaf5);box-shadow:0 4px 0 #90acc3;padding:9px 14px;cursor:pointer;color:var(--ink);font-weight:700}button:active{transform:translateY(3px);box-shadow:0 1px 0 #90acc3}button:focus-visible,a:focus-visible,input:focus-visible{outline:4px solid #f2a322;outline-offset:3px}button.active,button[aria-pressed=true]{background:linear-gradient(#3b93e4,#1265b4);color:white;border-color:#085caa;box-shadow:0 4px 0 #084c90}button:disabled{opacity:.5;cursor:default}.good{color:var(--green)}.bad{color:#b02038}.warm{background:linear-gradient(#ffead0,#ffc581)}.purple{background:linear-gradient(#ece0ff,#c9adf5)}.green{background:linear-gradient(#d6fff0,#93ddc1)}.pink{background:linear-gradient(#ffe2ef,#f4b3cd)}nav{position:sticky;top:0;z-index:25;background:#eaf5ff;border-bottom:2px solid #9ebbd8;padding:10px 18px;display:flex;flex-wrap:wrap;gap:9px;align-items:center}nav button::before{content:'◆ ';font-size:.8em}#bar{position:sticky;top:var(--navh,78px);z-index:24;background:#fffaf0;display:flex;flex-wrap:wrap;align-items:center;gap:10px;padding:8px 20px;box-shadow:0 2px 4px #adc1d1}#bar strong{flex:1}h1{font-size:clamp(27px,3vw,42px);margin:10px 0}h2{font-size:28px;margin:14px 0}h3{font-size:22px}p{line-height:1.7}main{padding:22px;max-width:1640px;margin:auto}body.full main{max-width:none;min-height:calc(100vh - 150px)}.intro{background:linear-gradient(110deg,#d8edff,#fff4d2);padding:24px;border-radius:18px;border-left:9px solid var(--blue)}.intro p{max-width:1000px}.tiles{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:18px;margin:22px 0}.tile{background:white;border:1px solid #bfd1e0;border-radius:15px;padding:20px;border-top:6px solid #4b99dd}.tile p{margin:8px 0}.small{font-size:15px;color:var(--muted)}.tools{display:flex;flex-wrap:wrap;gap:10px;align-items:center;margin:10px 0}.cardnav{position:sticky;top:var(--navh,56px);z-index:23;background:#e7f4ff;padding:10px;border-bottom:1px solid #aac6dc;display:flex;flex-wrap:wrap;gap:8px;align-items:center}.cardnav select{min-width:150px;max-width:100%;flex:1;padding:8px}.card{display:grid;grid-template-columns:minmax(0,1.55fr) minmax(350px,1fr);gap:22px;background:white;padding:24px;border-radius:16px;margin-top:16px;border-top:8px solid #237ec6;box-shadow:0 5px 18px #9ab6ca30}.question{font-size:26px;line-height:1.9;min-width:0}.question p{margin-top:8px}.support{font-size:23px;line-height:1.8;background:#f5f0ff;border-radius:12px;padding:18px;min-width:0;max-width:610px}.support .step{padding:8px 0;border-bottom:1px solid #cfc1e4}.options{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(100%,230px),1fr));gap:12px;margin:16px 0}.option{min-width:0;text-align:left;font-size:23px;white-space:normal;line-height:1.7;padding:12px;overflow-wrap:anywhere}.option .katex{white-space:normal}.choice-group{border:0;padding:4px 0 14px;margin:0;min-width:0}.choice-group legend{font-size:19px;font-weight:700}.answer{font-weight:700;color:#5b2193;font-size:25px;line-height:2}.source{font-size:14px;color:#556473;overflow-wrap:anywhere}svg.math-diagram{max-width:100%;width:400px;height:auto;display:block;margin:auto;background:#fbfdff;border:1px solid #bdd0df;border-radius:12px}.stamp{font-weight:900;color:#08754c;border:4px solid #08754c;padding:6px 16px;display:inline-block;transform:rotate(-4deg);margin:15px 5px}.katex{font-size:1em}.katex-display{margin:.4em 0;max-width:100%;overflow-x:auto;overflow-y:visible;padding:3px 0}.mathflow{overflow-wrap:anywhere;min-width:0}.concept{border-bottom:2px solid #a9c6d9;margin-bottom:25px;padding-bottom:20px}.concept .mathflow{font-size:24px;line-height:1.9}table{border-collapse:collapse;width:100%;margin:18px 0;background:white}td,th{border:1px solid #adc2d3;padding:10px;line-height:1.6;text-align:left}th{background:#d7e9fb}dialog{max-width:95vw;width:950px;border:2px solid #8dadc8;border-radius:15px;padding:22px}dialog::backdrop{background:#102a4499}#boardCanvas{position:fixed;inset:0;width:100vw;height:100vh;z-index:70;touch-action:none;pointer-events:none}#boardTools{position:fixed;bottom:15px;left:50%;transform:translateX(-50%);display:flex;flex-wrap:wrap;justify-content:center;gap:6px;z-index:80;background:#fffdf3;border:2px solid #b7a78a;border-radius:16px;padding:10px;width:min(96vw,1140px);box-shadow:0 5px 15px #0004}#boardTools[hidden]{display:none}#boardTools button{padding:6px 9px;font-size:16px}#captureUI{position:fixed;inset:0;z-index:100;background:#ffffff04;touch-action:none}#captureUI svg{width:100%;height:100%}.capture-hint{position:fixed;top:12px;left:50%;transform:translateX(-50%);background:#fff8d0;border:2px solid #a96012;padding:12px;border-radius:10px;z-index:101}.progress{background:#edf6f5;padding:12px;border-radius:10px}.game{min-height:350px;padding:22px;background:#fff;border-radius:18px;margin:15px 0;border-top:7px solid #8e65cf}.matchgrid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}.matchgrid button{min-height:85px}.badge{display:inline-block;border-radius:6px;background:#e2f2ff;padding:3px 7px}.lab{display:grid;grid-template-columns:minmax(280px,1fr) minmax(280px,1fr);gap:20px;background:#fff;padding:22px;border-radius:15px}.lab input[type=range]{width:100%}.foot{padding:18px;text-align:center;color:#506477}.notice{background:#fff3d2;padding:14px;border-left:5px solid #bf7d15}a{color:#1269ab}label{line-height:1.8}#toast{position:fixed;bottom:12px;right:18px;background:#18324b;color:white;padding:12px;border-radius:10px;z-index:120;max-width:90vw}#toast:empty{display:none}[hidden]{display:none!important}@media(max-width:900px){body{font-size:17px}main{padding:12px}.card{grid-template-columns:1fr;padding:15px}.question{font-size:23px}.support{font-size:22px;max-width:none}.lab{grid-template-columns:1fr}.matchgrid{grid-template-columns:repeat(2,minmax(0,1fr))}nav{padding:8px;gap:7px}nav button{font-size:16px;padding:7px}.option{font-size:21px}.answer{font-size:23px}}@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important;animation:none!important}}
.concept{display:grid;grid-template-columns:minmax(0,1fr) minmax(260px,320px);gap:10px 16px;align-items:start}.concept h2,.concept>p{grid-column:1/-1}.concept .mathflow{grid-column:1;align-self:center}.concept .diagram-frame{grid-column:2;grid-row:3}.concept .tools{grid-column:1/-1}.card .options{grid-template-columns:minmax(0,1fr)}@media(max-width:850px){.concept{grid-template-columns:minmax(0,1fr)}.concept h2,.concept>p,.concept .mathflow,.concept .diagram-frame,.concept .tools{grid-column:1}}:root{--ink:#192746;--muted:#4c5d7c;--blue:#126be8;--purple:#7738dd;--green:#07836f;--orange:#db5a10;--red:#d33261;background:#f3f6ff}body{background:radial-gradient(ellipse at 8% 0%,#d9eeff 0%,transparent 42%),linear-gradient(135deg,#f1f6ff 0%,#f5f0ff 54%,#fff4e8 100%)}nav{background:linear-gradient(100deg,#cfe6ff,#e4d7ff 58%,#ffe3d1);border-bottom:2px solid #8caaea;box-shadow:0 4px 12px #28487b26}nav button{background:linear-gradient(160deg,#ffffff,#d8e8ff);border-color:#91afe2;box-shadow:0 3px 0 #829dcc,0 5px 10px #36558a20}#bar{background:linear-gradient(100deg,#fff0c9,#e5f4ff 55%,#eee2ff);box-shadow:0 4px 12px #28487b20}button,.button{background:linear-gradient(155deg,#ffffff 0%,#e7f0ff 62%,#d6e3ff 100%);border-color:#86a7df;box-shadow:0 3px 0 #718fc6,0 7px 14px #3c5a8b20;transition:transform .16s ease,filter .16s ease,box-shadow .16s ease}button:hover,.button:hover{filter:saturate(1.25);transform:translateY(-2px);box-shadow:0 5px 0 #718fc6,0 10px 18px #3c5a8b2b}.intro{background:linear-gradient(112deg,#b8e2ff 0%,#e5d0ff 55%,#ffe4a3 100%);border-left-color:#6d39d4;box-shadow:0 5px 0 #9b82d0,0 12px 26px #424b9d26;padding:20px}.tiles{gap:14px;margin:16px 0}.tile{background:linear-gradient(150deg,#ffffff 8%,#f0f5ff 100%);border-color:#b3c9ef;border-top-color:#1879ec;border-radius:16px;padding:16px;box-shadow:0 3px 0 #8ea8d7,0 9px 18px #39588a20;transition:transform .16s ease,box-shadow .16s ease}.tile:nth-child(4n+2){border-top-color:#833bdc}.tile:nth-child(4n+3){border-top-color:#0d9a85}.tile:nth-child(4n){border-top-color:#e57027}.tile:hover{transform:translateY(-3px);box-shadow:0 5px 0 #8ea8d7,0 14px 24px #39588a30}.card{gap:16px;padding:18px;margin-top:12px;border:1px solid #bfd0ef;border-top:7px solid #7745df;background:linear-gradient(145deg,#ffffff,#f3f7ff);box-shadow:0 4px 0 #91a8d4,0 12px 26px #2f4d8024}.support{background:linear-gradient(145deg,#f6eaff,#e8ddff);border:1px solid #d3bdf4;box-shadow:inset 0 1px #fff,0 4px 12px #6d4aa320;padding:14px}.option{background:linear-gradient(145deg,#ffffff,#e8f2ff);border-color:#9bb8ec;box-shadow:0 3px 0 #91a8d4,0 5px 12px #36558a18}.option[aria-pressed=true]{background:linear-gradient(140deg,#b9dcff,#cfc2ff);border-color:#6643c5}.choice-group{border:1px solid #cfdbf3;border-radius:13px;padding:10px 12px;margin:8px 0;background:linear-gradient(145deg,#fff,#f7f5ff)}.math-diagram{border:0!important;border-radius:11px;background:linear-gradient(145deg,#fff,#e5f2ff);filter:none;shape-rendering:geometricPrecision;text-rendering:geometricPrecision}.diagram-frame{margin:8px auto;padding:9px 12px 7px;max-width:340px;border:1px solid #9fb9e8;border-radius:17px;background:linear-gradient(145deg,#ffffff,#e4efff 68%,#eee5ff);box-shadow:inset 0 1px #ffffff,0 4px 0 #8098ca,0 10px 22px #354f8229}.diagram-frame figcaption{margin:0 4px 5px;padding:4px 8px;color:#283964;font-size:17px;font-weight:800;letter-spacing:.02em;background:linear-gradient(90deg,#d8ebff,#efe2ff);border-radius:8px}.diagram-frame .math-diagram{width:100%;height:auto;background:transparent;box-shadow:none}.math-diagram text{fill:#263653;font-family:'Microsoft JhengHei','Noto Sans TC',sans-serif;font-weight:600;text-rendering:geometricPrecision}.diagram-note{margin:5px 4px 0;color:#43536f;font-size:14px;font-weight:600;line-height:1.45;text-rendering:geometricPrecision}.concept{gap:8px 18px;margin-bottom:16px;padding-bottom:14px;border-bottom-color:#9a83dc}.concept .mathflow{font-size:22px;line-height:1.65;padding:12px 14px;border-radius:13px;background:linear-gradient(145deg,#ffffff,#eaf2ff);border:1px solid #cad8f3;box-shadow:inset 0 1px #fff,0 3px 0 #afbee0,0 8px 16px #475e9220}.lab,.game{background:linear-gradient(145deg,#ffffff,#eaf2ff 58%,#f2eaff);border:1px solid #bfd0ef;box-shadow:0 4px 0 #91a8d4,0 11px 24px #354f8224;padding:16px}.game{border-top:7px solid #793bdd}.progress{background:linear-gradient(100deg,#d4f5ed,#e2edff);border-left:5px solid #119b82;padding:9px 12px}.notice{background:linear-gradient(100deg,#fff0bd,#ffe0ca);border-left-color:#e07a17;padding:10px 12px}.badge{background:linear-gradient(135deg,#d4eaff,#eadbff);color:#3c3483;box-shadow:0 2px 5px #344f7b20}table{border-radius:12px;overflow:hidden;box-shadow:0 4px 0 #a3b6dc,0 10px 20px #354f8220}th{background:linear-gradient(100deg,#bcdcff,#dccbff);color:#1f3154}td{background:#fff}dialog{background:linear-gradient(145deg,#fff,#f0f4ff);box-shadow:0 14px 40px #152b5470}.foot{padding:10px}#boardTools{background:linear-gradient(135deg,#fff,#e7efff,#f4e8ff);border-color:#7954ce;box-shadow:0 5px 0 #937fc2,0 12px 24px #243c682e}.page-tag{display:inline-flex;align-items:center;vertical-align:middle;margin-left:12px;padding:4px 10px;border-radius:999px;background:linear-gradient(135deg,#1465dc,#7838d9);color:#fff;font-size:.58em;line-height:1.3;font-weight:800;box-shadow:0 2px 0 #4e48a5,0 4px 8px #33478a30;white-space:nowrap}.diagram-frame{max-width:340px;cursor:zoom-in}.diagram-frame:focus-visible{outline:4px solid #f2a322;outline-offset:3px}.diagram-frame figcaption{display:flex;justify-content:space-between;align-items:center;gap:8px}.diagram-open-hint{font-size:12px;font-weight:700;color:#4b55a0;white-space:nowrap}.diagram-viewer{resize:both;overflow:auto;position:fixed;inset:auto;margin:0;padding:0;width:min(520px,88vw);height:min(560px,82vh);max-width:calc(100vw - 12px);max-height:calc(100vh - 12px);border:2px solid #7254d1;border-radius:16px;background:linear-gradient(145deg,#fff,#edf3ff 62%,#efe7ff);box-shadow:0 8px 0 #8a7bc0,0 20px 48px #172b5570;z-index:200}.diagram-viewer[open]{display:flex;flex-direction:column}.diagram-window-bar{flex:0 0 auto;min-height:48px;display:flex;align-items:center;gap:10px;padding:8px 10px 8px 14px;background:linear-gradient(100deg,#d9ebff,#e7dcff 65%,#ffe7d1);border-bottom:1px solid #a8b8e0;cursor:move;touch-action:none;user-select:none}.diagram-window-bar strong{font-size:16px}.diagram-window-bar span{font-size:12px;color:#43516f}.diagram-window-bar button{margin-left:auto;padding:2px 10px;font-size:20px;line-height:1}.diagram-stage{flex:1;min-width:0;min-height:0;overflow:auto;padding:10px;display:flex}.diagram-stage .diagram-frame{width:100%;max-width:none;height:100%;min-height:0;margin:0;display:flex;flex-direction:column;align-items:stretch;cursor:default}.diagram-stage .diagram-open-hint{display:none}.diagram-stage .math-diagram{width:100%;height:0;min-height:120px;max-width:none;flex:1}.diagram-stage .diagram-note{flex:0 0 auto}.question-visual-answer{display:grid;grid-template-columns:minmax(220px,320px) minmax(0,1fr);gap:14px;align-items:start}.question-visual-answer>.diagram-frame{grid-column:1;grid-row:1;width:100%;max-width:320px;margin:0}.question-visual-answer>#groups{grid-column:2;min-width:0}.question-visual-answer .choice-group{min-width:0}@media(max-width:1200px){.question-visual-answer{grid-template-columns:minmax(0,1fr)}.question-visual-answer>.diagram-frame,.question-visual-answer>#groups{grid-column:1;grid-row:auto}}body{font-size:16px}h1{font-size:clamp(24px,2.2vw,34px);margin:8px 0}h2{font-size:23px;margin:10px 0}button,.button{font-size:15px;padding:7px 10px;border-radius:10px}.tiles{gap:12px;margin:14px 0}.tile{padding:14px}.card{gap:12px;padding:14px;margin-top:10px}.cardnav{gap:6px;padding:7px}.cardnav button,.cardnav select{font-size:14px;padding:5px 8px;min-height:34px}.question{font-size:19px;line-height:1.5}.question-visual-answer{grid-template-columns:minmax(180px,280px) minmax(0,1fr);gap:10px}.question-visual-answer>.diagram-frame{max-width:280px;padding:7px 9px 6px}.question-visual-answer .options{gap:7px;margin:8px 0}.choice-group{padding:6px 8px;margin:5px 0}.choice-group legend{font-size:15px}.option{font-size:17px;line-height:1.38;padding:7px 9px;border-radius:10px}.support{font-size:17px;line-height:1.5;padding:11px}.support h2{font-size:20px}.support .tools{gap:6px;margin:7px 0}.support button,.card .tools button{font-size:14px;padding:5px 8px}.card .tools{gap:6px;margin:7px 0}.source{font-size:12px;line-height:1.45;margin:6px 0}nav{flex-wrap:nowrap;overflow-x:auto;gap:5px;padding:6px 10px;scrollbar-width:thin}nav button{flex:0 0 auto;font-size:13px;padding:5px 8px;border-radius:9px;box-shadow:0 2px 0 #718fc6,0 3px 7px #3c5a8b18}nav button::before{content:none}.brand{flex:0 0 auto;font-size:14px;white-space:nowrap;margin-right:4px}.nav-state{flex:0 0 auto;font-size:11px;white-space:nowrap}.cardnav{top:var(--navh,52px);gap:5px;padding:6px}.cardnav button,.cardnav select{min-height:30px;font-size:13px;padding:4px 7px}.card{grid-template-columns:minmax(0,1fr) minmax(280px,400px);gap:12px;padding:12px;margin-top:8px;border-top-width:5px}.question{font-size:18px;line-height:1.42}.question h2{font-size:20px;margin:6px 0}.question-visual-answer{grid-template-columns:minmax(250px,320px) minmax(0,1fr);gap:9px}.question-visual-answer>.diagram-frame{max-width:320px;padding:6px 8px}.question-visual-answer>.diagram-frame figcaption{font-size:13px;line-height:1.25}.question-visual-answer>.diagram-frame .math-diagram{max-height:320px}.question-visual-answer .options{gap:5px;margin:6px 0}.choice-group{padding:4px 6px;margin:3px 0}.choice-group legend{font-size:14px}.option{font-size:15px;line-height:1.25;padding:5px 7px;border-radius:8px}.support{font-size:15px;line-height:1.42;padding:9px;max-width:none}.support h2{font-size:17px;margin:4px 0 6px}.support .step{padding:4px 0}.support p{margin:5px 0}.support .tools,.card .tools{gap:5px;margin:5px 0}.support button,.card .tools button{font-size:12px;padding:4px 6px;box-shadow:0 2px 0 #718fc6,0 4px 8px #3c5a8b18}main{padding:10px 14px}.card .source{margin:4px 0}body:has(.card) .foot{display:none}@media(max-width:1080px){.card{grid-template-columns:minmax(0,1fr)}.question-visual-answer{grid-template-columns:minmax(210px,280px) minmax(0,1fr)}.question-visual-answer>.diagram-frame{max-width:280px}}@media(max-width:720px){.question-visual-answer{grid-template-columns:minmax(0,1fr)}.question-visual-answer>.diagram-frame{max-width:320px;margin:0 auto}.brand{font-size:12px}}.lab .reciprocal-pairs{display:grid;gap:7px;max-width:820px;margin:10px 0 12px}.reciprocal-head,.reciprocal-row{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:24px;align-items:center}.reciprocal-head{font-size:14px;font-weight:800;color:#4d5e87;padding:0 10px}.reciprocal-head span:last-child{text-align:left}.reciprocal-row{grid-template-columns:minmax(0,1fr) 24px minmax(0,1fr);gap:8px}.reciprocal-value{min-width:0;display:flex;justify-content:space-between;align-items:center;gap:8px;padding:9px 11px;border:1px solid #91b3e8;border-radius:10px;background:linear-gradient(120deg,#e2f1ff,#f6f0ff);box-shadow:0 2px 0 #8198c6;font-size:16px}.reciprocal-inverse{background:linear-gradient(120deg,#f1e9ff,#fff0d9);border-color:#b69be2}.reciprocal-value strong{font-variant-numeric:tabular-nums;white-space:nowrap}.reciprocal-mark{text-align:center;color:#6540bb;font-size:18px;font-weight:900}.lab #labValues>.small{max-width:820px;font-size:13px;line-height:1.4;margin:6px 0}@media(max-width:600px){.lab .reciprocal-row{grid-template-columns:minmax(0,1fr) 18px minmax(0,1fr);gap:4px}.reciprocal-value{font-size:13px;padding:7px 6px;gap:4px}.reciprocal-head{font-size:12px}}body:has(.lab) main{height:calc(100dvh - var(--navh,52px));min-height:0;max-width:none;overflow:hidden;display:flex;flex-direction:column;padding:6px 12px}body:has(.lab) main>h1{flex:0 0 auto;font-size:22px;margin:0 0 5px}.lab{flex:1;min-height:0;grid-template-columns:minmax(250px,.85fr) minmax(400px,1.15fr);gap:12px;padding:10px;align-items:center}.lab>section{min-width:0}.lab h2{font-size:18px;margin:3px 0 6px}.lab label{display:grid;grid-template-columns:auto minmax(120px,1fr);gap:8px;align-items:center;line-height:1.3;font-size:14px}.lab .tools{gap:4px;margin:5px 0}.lab .tools button,.lab>section>button{font-size:12px;padding:4px 7px;min-height:28px}.lab #labPlot{display:flex;align-items:center;justify-content:center;min-height:0}.lab #labPlot .diagram-frame{width:100%;max-width:min(100%,420px);margin:auto;padding:5px}.lab #labPlot .math-diagram{width:auto;max-width:100%;max-height:calc(100dvh - 235px)}#labValues>p{margin:3px 0;line-height:1.3;font-size:14px}.lab .reciprocal-pairs{gap:4px;margin:5px 0 6px}.lab .reciprocal-row{gap:5px}.lab .reciprocal-value{padding:5px 8px;font-size:14px;line-height:1.2}.lab .reciprocal-mark{font-size:15px}.lab #labValues>.small{font-size:11px;line-height:1.25;margin:4px 0}.lab>section>p{font-size:13px;line-height:1.35;margin:5px 0}body:has(.lab) .foot{display:none}@media(max-height:700px) and (min-width:901px){body:has(.lab) main>h1{font-size:19px}.lab{gap:8px;padding:7px}.lab #labPlot .math-diagram{max-height:calc(100dvh - 200px)}.lab .reciprocal-value{padding:4px 7px}.lab>section>p{font-size:12px;margin:3px 0}}@media(max-width:900px){body:has(.lab) main{height:auto;min-height:0;overflow:visible;display:block;padding:10px 12px}.lab{grid-template-columns:minmax(0,1fr);height:auto;padding:10px}.lab #labPlot .math-diagram{max-height:42vh}.lab label{grid-template-columns:1fr}.lab .tools{flex-wrap:wrap}}.concept{grid-template-columns:minmax(0,1.45fr) minmax(350px,.9fr);gap:8px 20px;align-items:start;padding:14px 16px;margin:16px auto;background:linear-gradient(120deg,#ffffffef,#f4f6ffed);border:1px solid #cbd6f2;border-top:4px solid #7653d4;border-radius:14px;box-shadow:0 3px 0 #a6add1,0 8px 20px #45558a18}.concept h2,.concept>p{grid-column:1/-1}.concept h2{margin:2px 0;font-size:22px}.concept>p{margin:2px 0 6px;font-size:16px;line-height:1.45}.concept .concept-body{grid-column:1;grid-row:3;min-width:0;align-self:start;display:grid;align-content:start;gap:10px}.concept .diagram-frame{grid-column:2;grid-row:3;width:100%;max-width:500px;margin:0 auto;align-self:start}.concept .diagram-frame .math-diagram{width:100%;max-width:460px}.concept-steps{counter-reset:concept-step;list-style:none;padding:0;margin:0;display:grid;gap:8px}.concept-steps li{counter-increment:concept-step;display:grid;grid-template-columns:36px minmax(0,1fr);column-gap:10px;align-items:center;padding:9px 12px;border:1px solid #b4c7ef;border-radius:11px;background:linear-gradient(110deg,#eaf4ff,#f2edff);box-shadow:0 2px 0 #a0add2}.concept-steps li:before{content:counter(concept-step);grid-row:span 2;width:30px;height:30px;display:grid;place-items:center;border-radius:50%;background:linear-gradient(145deg,#287be4,#8241d2);color:white;font-weight:800}.concept-steps li b{font-size:16px}.concept-steps li span{font-size:15px;line-height:1.4}.concept-alert{margin:0;padding:10px 12px;border-left:5px solid #e49a24;border-radius:8px;background:linear-gradient(100deg,#fff1d6,#fff9eb);font-size:15px;line-height:1.45}.concept .concept-body .tools{margin:0;gap:7px}.concept .concept-body .tools button{font-size:14px;padding:6px 9px}@media(max-width:900px){.concept{grid-template-columns:minmax(0,1fr)}.concept h2,.concept>p,.concept .concept-body,.concept .diagram-frame{grid-column:1;grid-row:auto}.concept .diagram-frame{max-width:420px}.concept .concept-body{grid-row:auto}}.concept .diagram-frame{max-width:420px}.concept .diagram-frame .math-diagram{max-width:380px;max-height:min(40vh,380px)}@media(max-width:900px){.concept .diagram-frame{max-width:360px}.concept .diagram-frame .math-diagram{max-height:38vh}}.option .katex{font-size:1.12em;white-space:normal}.option .katex .mfrac{font-size:1.18em;vertical-align:-.04em}.option{line-height:1.4;padding-top:6px;padding-bottom:6px}.concept-bridge{margin:0;padding:10px 12px;border-left:5px solid #287be4;border-radius:8px;background:linear-gradient(100deg,#e5f2ff,#f3f0ff);font-size:15px;line-height:1.45}.stack-frac{display:inline-grid;grid-template-rows:auto auto;vertical-align:middle;text-align:center;line-height:1.05;min-width:1.35em;margin:0 .08em;font-size:1.08em;font-variant-numeric:tabular-nums}.stack-frac>span:first-child{border-bottom:1px solid currentColor;padding:0 .12em .06em}.stack-frac>span:last-child{padding:.05em .12em 0}.matchgrid button{display:flex;align-items:center;justify-content:center;min-height:76px}.diagram-frame>figcaption:not(.diagram-note){display:grid;grid-template-columns:minmax(0,1fr);gap:2px;align-items:start}.diagram-frame>figcaption:not(.diagram-note)>strong{display:block;white-space:nowrap;font-size:clamp(11px,.92em,15px);line-height:1.2;font-weight:700}.diagram-frame>figcaption:not(.diagram-note)>.diagram-open-hint{display:block;justify-self:end;font-size:11px;line-height:1.2;white-space:nowrap}.katex .mfrac{font-size:1.28em}.option .katex .mfrac{font-size:1.28em}