:root{color-scheme:light;--navy:#13263e;--ink:#16324b;--muted:#5c6f80;--yellow:#ffd84d;--paper:#f3f6f9}
    [hidden]{display:none!important}
    *{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font-family:system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;line-height:1.45}
    .header{height:60px;background:var(--navy);color:white;display:flex;align-items:center}.header-inner{width:min(760px,100%);margin:auto;padding:0 24px;display:flex;align-items:center;justify-content:space-between;gap:16px}
    .brand{color:white;text-decoration:none;font-size:22px;font-weight:800;letter-spacing:-.8px}.brand span{color:var(--yellow)}.header-label{font-size:13px;color:#d5e2ed;font-weight:600}
    main{max-width:760px;margin:auto;padding:28px 24px 20px}.title-row{display:flex;align-items:center;justify-content:space-between;gap:12px}h1{margin:0;font-size:clamp(25px,4vw,34px);letter-spacing:-.8px;line-height:1.2}.total{font-size:13px;font-weight:650;background:#e5edf4;border-radius:8px;padding:6px 10px;white-space:nowrap}.intro{margin:8px 0 22px;color:var(--muted);font-size:15px}
    .selector{display:flex;align-items:center;gap:12px;margin-bottom:17px}.selector label{font-size:14px;font-weight:650;white-space:nowrap}select{font:inherit;font-size:14px;color:var(--ink);background:white;border:1px solid #cbd8e3;border-radius:9px;min-height:44px;padding:8px 30px 8px 12px;width:100%;min-width:0}
    .deck-meta{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-bottom:9px;color:var(--muted);font-size:13px}.position{font-weight:700;color:var(--ink);font-variant-numeric:tabular-nums}.order{font-size:12px}
    .card{display:block;position:relative;width:100%;height:330px;padding:0;border:0;border-radius:20px;background:transparent;font:inherit;text-align:left;cursor:pointer;perspective:1400px;-webkit-tap-highlight-color:transparent;touch-action:manipulation}
    button:focus-visible,a:focus-visible,select:focus-visible{outline:3px solid #ddaa19;outline-offset:4px}.inner{position:relative;display:block;width:100%;height:100%;transform-style:preserve-3d;transition:transform .5s cubic-bezier(.2,.7,.2,1)}.card[aria-pressed="true"] .inner{transform:rotateY(180deg)}.card.changing .inner{transition:none}
    .face{position:absolute;inset:0;display:flex;flex-direction:column;justify-content:space-between;border-radius:20px;padding:25px 28px;backface-visibility:hidden;-webkit-backface-visibility:hidden;box-shadow:0 8px 24px #173e6210;overflow:hidden}.front{background:var(--navy);color:white;border:1px solid #2b5275}.back{background:white;color:var(--ink);border:1px solid #cbd8e3;transform:rotateY(180deg)}
    .meta{display:flex;align-items:center;justify-content:space-between;gap:12px;font-size:12px;font-weight:750;letter-spacing:.65px}.front .meta{color:#d0dfec}.back .meta{color:var(--muted)}.number{color:var(--yellow);white-space:nowrap;font-variant-numeric:tabular-nums}.answer-label{color:var(--navy);display:inline-flex;align-items:center;gap:7px}.answer-label:before{content:"";width:7px;height:7px;background:var(--yellow);border-radius:50%}
    .question{display:flex;align-items:center;flex:1;margin:15px 0;font-size:clamp(24px,3.4vw,31px);line-height:1.3;font-weight:700;letter-spacing:-.5px;overflow-wrap:break-word}.answer-area{display:flex;flex-direction:column;justify-content:center;flex:1;min-width:0;margin:15px 0}.answer{display:block;font-size:clamp(23px,3.4vw,32px);line-height:1.35;font-weight:700;letter-spacing:-.4px;overflow-wrap:break-word}.answer.short{font-size:clamp(32px,5vw,44px)}.answer-note{display:block;font-size:14px;color:var(--muted);margin-top:12px;line-height:1.45}.answer-note[hidden]{display:none}
    .answer.equation{font-size:var(--equation-size,clamp(10px,3.1vw,32px));width:100%;white-space:nowrap;letter-spacing:-.02em;overflow-wrap:normal}.equation-text{display:inline-block;white-space:nowrap}.hint{display:flex;gap:8px;align-items:center;font-size:13px;font-weight:600}.front .hint{color:#d0dfec}.back .hint{color:var(--muted)}.flip-icon{font-size:19px;line-height:1}
    .navigation{display:flex;align-items:center;gap:12px;margin-top:17px}.navigation button{flex:1;font:inherit;font-size:15px;font-weight:650;border:1px solid #cbd8e3;border-radius:10px;min-height:46px;background:white;color:var(--navy);cursor:pointer}.navigation .next{background:var(--navy);color:white;border-color:var(--navy)}button:disabled{opacity:.42;cursor:default}.tools{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-top:12px}.tools button{font:inherit;font-size:13px;background:transparent;border:0;min-height:44px;color:var(--navy);padding:6px 8px;cursor:pointer}.tools button:hover{background:#e5edf4;border-radius:8px}.tools button:disabled:hover{background:transparent}
    footer{margin-top:18px;font-size:12px;color:var(--muted);text-align:center}footer a{color:var(--muted);text-underline-offset:3px}.noscript{padding:16px;background:white;border:1px solid #cbd8e3;border-radius:10px;margin-bottom:16px}
    @media(hover:hover){.card:hover .front{background:#1e496f}.card:hover .back{border-color:#7491aa}.navigation button:not(:disabled):hover{filter:brightness(.96)}}
    @media(max-width:650px){.header{height:52px}.header-inner{padding:0 16px}.brand{font-size:20px}.header-label{font-size:12px}main{padding:20px 16px 16px}.intro{font-size:14px;margin:7px 0 17px}.total{font-size:12px;padding:5px 8px}.selector{gap:9px;margin-bottom:15px}.card{height:310px;border-radius:16px}.face{padding:20px 19px;border-radius:16px}.meta{font-size:11px;letter-spacing:.15px}.question{font-size:24px;line-height:1.3;margin:12px 0}.answer-area{margin:12px 0}.answer{font-size:23px}.answer-note{font-size:13px;margin-top:9px}.hint{font-size:12px}.navigation{margin-top:15px;gap:10px}footer{margin-top:10px}}
    @media(max-width:360px){.title-row{align-items:flex-start}.total{font-size:11px}.question{font-size:22px}.answer{font-size:21px}.card{height:310px}.face{padding:19px 16px}.meta{gap:8px;font-size:10.5px}.header-label{font-size:11px}}
    @media(prefers-reduced-motion:reduce){.inner{transition:none}}
    .breadcrumbs{display:flex;flex-wrap:wrap;align-items:center;gap:9px;font-size:13px;color:var(--muted);margin-bottom:16px}.breadcrumbs a{color:var(--navy);text-underline-offset:3px;min-height:30px;display:inline-flex;align-items:center}
    .confidence{display:flex;gap:10px;align-items:center;margin-top:12px}.confidence button{font:inherit;font-size:13px;font-weight:650;min-height:44px;border:1px solid #cbd8e3;border-radius:9px;background:white;color:var(--navy);padding:9px 12px;cursor:pointer}.confidence #hide-card{flex:1;background:#e5edf4}.confidence #hidden-cards{white-space:nowrap}.action-notice{margin:9px 0 0;font-size:12px;color:var(--muted);line-height:1.5;min-height:18px}
    .hidden-panel{margin-top:16px;padding:16px;border:1px solid #cbd8e3;border-radius:12px;background:white}.hidden-heading{display:flex;align-items:center;gap:8px;flex-wrap:wrap}.hidden-heading h2{font-size:18px;margin:0 auto 0 0}.hidden-heading button,.hidden-list button{font:inherit;font-size:13px;min-height:44px;padding:8px 11px;border:1px solid #cbd8e3;border-radius:8px;background:white;color:var(--navy);cursor:pointer}.hidden-list{list-style:none;margin:12px 0 0;padding:0}.hidden-list li{display:flex;gap:12px;align-items:center;padding:10px 0;border-top:1px solid #e5edf4}.hidden-list li>span{flex:1;min-width:0;font-size:14px;line-height:1.45}.hidden-list button{flex-shrink:0}.empty-state{height:330px;padding:28px;border:1px solid #cbd8e3;border-radius:20px;background:white;display:flex;flex-direction:column;justify-content:center;align-items:center;text-align:center}.empty-state h2{font-size:25px;margin:0 0 12px}.empty-state p{font-size:16px;color:var(--muted);margin:0;max-width:420px}.navigation button{font-size:14px}.tools{margin-top:7px}
    @media(max-width:650px){.breadcrumbs{margin-bottom:12px}.confidence{gap:8px}.confidence button{padding:8px 9px;font-size:12px}.empty-state{height:310px;padding:20px;border-radius:16px}.navigation{gap:8px}.navigation button{font-size:13px}.hidden-panel{padding:12px}}

    .diagram-card{height:410px}.diagram-card .face{padding:20px;border-radius:4px;box-shadow:none;background:#fff;color:#111;border:1.5px solid #111;display:grid;gap:10px;justify-content:normal}.diagram-card .front{grid-template-rows:auto auto minmax(0,1fr) auto}.diagram-card .back{grid-template-rows:auto minmax(0,1fr) auto auto}.diagram-card .front .meta,.diagram-card .front .hint,.diagram-card .back .hint,.diagram-card .number,.diagram-card .answer-label{color:#111}.diagram-card .answer-label:before{background:#111}.diagram-card .question{display:block;margin:0;flex:none;font-size:21px;line-height:1.3;letter-spacing:0}.diagram-figure{display:block;min-height:0;min-width:0;width:100%;height:100%;margin:0}.diagram-figure img{display:block;width:100%;height:100%;object-fit:contain;user-select:none}.diagram-card .answer-area{margin:0;flex:none;display:block}.diagram-card .answer,.diagram-card .answer.short{font-size:27px;line-height:1.25}.diagram-card .answer-note{color:#111;margin-top:6px}.diagram-mark{white-space:nowrap;font-weight:500;letter-spacing:0}.hidden-list img{width:80px;height:50px;object-fit:contain;background:#fff;flex-shrink:0;border:1px solid #cbd8e3}
    @media(max-width:650px){.diagram-card{height:360px}.diagram-card .face{padding:16px;gap:8px}.diagram-card .question{font-size:19px}.diagram-card .answer,.diagram-card .answer.short{font-size:24px}.diagram-card .meta{font-size:10.5px;gap:7px}.hidden-list li{gap:8px}.hidden-list img{width:64px;height:44px}}