:root{--bg: #f1ede1;--surface: #ffffff;--ink: #1e2a23;--ink-2: #fbf9f3;--ink-3: #f3f0e7;--paper: #f6f3eb;--ledger: #eaf2e7;--credit: #35784f;--credit-dim: #eaf2e7;--credit-line: #cbe0c8;--debit: #bc4b3c;--debit-dim: #f7e7e3;--debit-line: #e8cfc9;--gold: #c4633e;--gold-deep: #b08a2e;--line: #e4ddcc;--line-soft: #ebe5d6;--line-strong: #c9c1ad;--muted: #8a8578;--soft: #6b7268;--faint: #b3ac9b;--radius: 14px;--font-display: "Newsreader", Georgia, serif;--font-logo: "Instrument Serif", Georgia, serif;--font-body: "IBM Plex Sans", -apple-system, sans-serif;--font-mono: "IBM Plex Mono", ui-monospace, monospace}*{box-sizing:border-box;margin:0;padding:0}html,body{height:100%}body{background:var(--bg);color:var(--ink);font-family:var(--font-body);-webkit-font-smoothing:antialiased}a{color:var(--gold);text-decoration:none}a:hover{text-decoration:underline}.app{min-height:100dvh;display:flex;justify-content:center}.col{width:100%;max-width:430px;padding:22px 20px 118px;position:relative}.sidebar{display:none;flex-direction:column;gap:4px;width:232px;padding:48px 20px 32px;position:sticky;top:0;height:100dvh;flex-shrink:0}.sidebar-brand{display:flex;align-items:center;gap:10px;padding:0 12px;margin-bottom:34px}.sidebar button{display:flex;align-items:center;gap:12px;border:none;text-align:left;background:transparent;border-radius:12px;padding:12px 14px;font-size:14px;font-weight:500;color:#9a9385;min-height:44px;width:100%}.sidebar button.active{background:var(--surface);color:var(--ink)}.sidebar .streak-chip{margin-top:auto}.mobile-head{display:flex;align-items:center;justify-content:center;position:relative;margin-bottom:24px}.brand{display:flex;align-items:center;gap:11px}.wordmark{font-family:var(--font-logo);font-size:29px;font-weight:400;letter-spacing:.005em;line-height:1}.wordmark em{font-style:normal;color:var(--gold)}.streak-chip{font-family:var(--font-mono);font-size:11.5px;color:var(--muted);border:1px solid var(--line);border-radius:99px;padding:5px 11px;background:var(--ink-2);text-align:center}.mobile-head .streak-chip{position:absolute;right:0;top:50%;transform:translateY(-50%)}@media (min-width: 768px){.col{max-width:600px;padding-top:40px}.grid-2up{display:grid;grid-template-columns:1fr 1fr;align-items:stretch}}@media (min-width: 960px){.sidebar{display:flex}.bottom-nav,.mobile-head{display:none}.col{max-width:640px;padding-top:48px;padding-bottom:48px}}h1,h2,h3{font-family:var(--font-display);font-weight:600;letter-spacing:-.01em}h1{font-size:26px}h2{font-size:19px}h3{font-size:17px}.mono{font-family:var(--font-mono)}.muted{color:var(--muted)}.small{font-size:12.5px}button{font-family:var(--font-body);border:1px solid var(--line);background:var(--surface);color:var(--ink);border-radius:12px;padding:12px 16px;font-size:14.5px;font-weight:500;cursor:pointer;transition:transform .06s ease,background .15s ease,border-color .15s ease;-webkit-tap-highlight-color:transparent}button:active{transform:scale(.98)}button:focus-visible{outline:2px solid var(--gold);outline-offset:2px}button:disabled{opacity:.45;cursor:default}.btn-primary{background:var(--ink);color:var(--paper);border-color:var(--ink);font-weight:600}.btn-credit{background:var(--credit-dim);border-color:var(--credit-line);color:var(--credit);font-weight:600}.btn-debit{background:var(--debit-dim);border-color:var(--debit-line);color:var(--debit);font-weight:600}.btn-ghost{background:transparent}.btn-dashed{background:transparent;border:1px dashed var(--line-strong);color:var(--soft);font-size:13.5px}.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:16px}.paper-card{background:var(--surface);color:var(--ink);border:1px solid var(--line);border-radius:16px;padding:22px}.subtle-card{background:var(--ink-2);border:1px solid var(--line-soft);border-radius:var(--radius);padding:16px}.explain-card{background:#fbf7ec;border:1px solid #e7dfc8;border-radius:var(--radius);padding:18px 19px}.row{display:flex;align-items:center;gap:10px}.stack{display:flex;flex-direction:column;gap:10px}.grid2{display:grid;grid-template-columns:1fr 1fr;gap:10px}.grid4{display:grid;grid-template-columns:repeat(4,1fr);gap:7px}.pill{display:inline-block;font-family:var(--font-mono);font-size:11px;letter-spacing:.06em;padding:3px 9px;border-radius:99px;border:1px solid var(--line);background:var(--ink-2);color:var(--muted)}.pill-hot{border-color:var(--gold);color:var(--gold);background:transparent}.progress-track{height:4px;background:var(--ink-3);border-radius:99px;overflow:hidden}.progress-fill{height:100%;background:var(--credit);border-radius:99px;transition:width .25s ease}.choice{display:flex;gap:12px;align-items:baseline;text-align:left;width:100%;min-height:52px;padding:14px 15px;font-weight:500;font-size:14.5px;line-height:1.5;border-width:1.5px;border-radius:12px}.choice .letter{font-family:var(--font-mono);font-size:12px;color:var(--faint);flex-shrink:0}.choice .choice-text{flex:1}.choice.correct{background:var(--credit-dim);border-color:var(--credit);color:#274f38}.choice.correct .letter{color:var(--credit)}.choice.wrong{background:var(--debit-dim);border-color:var(--debit);color:#7a3129}.choice.wrong .letter{color:var(--debit)}.choice.faded{color:#9a9385}.choice.picked{border-color:var(--ink)}.choice.picked .letter{color:var(--ink)}.taccount{font-family:var(--font-mono);font-size:12.5px;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);overflow:hidden}.taccount-head{display:grid;grid-template-columns:1fr 1fr;border-bottom:2px solid var(--ink);text-align:center}.taccount-head>div{padding:8px;letter-spacing:.08em;font-size:11px}.taccount-head>div:first-child{border-right:1px solid var(--line);color:var(--debit)}.taccount-head>div:last-child{color:var(--credit)}.tline{display:grid;grid-template-columns:1fr 1fr}.tline>div{padding:6px 10px;border-right:1px solid var(--line);min-height:28px}.tline>div:last-child{border-right:none}.tline .memo{color:var(--muted);font-size:11px;display:block}.flash{perspective:1200px;min-height:260px;cursor:pointer}.flash-inner{position:relative;width:100%;min-height:260px;transition:transform .5s;transform-style:preserve-3d}.flash.flipped .flash-inner{transform:rotateY(180deg)}.flash-face{position:absolute;top:0;right:0;bottom:0;left:0;backface-visibility:hidden;display:flex;flex-direction:column;justify-content:center;padding:26px;border-radius:18px}.flash-front{background:var(--surface);border:1px solid var(--line);color:var(--ink)}.flash-back{background:var(--ink);color:var(--paper);transform:rotateY(180deg)}.match-grid{display:grid;grid-template-columns:1fr 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button{background:transparent;border:none;border-radius:16px;display:flex;flex-direction:column;align-items:center;gap:3px;font-size:10.5px;padding:9px 2px 7px;color:#9a9385;font-weight:500;min-height:52px}.bottom-nav button.active{color:var(--ink);background:var(--bg)}.eyebrow{font-family:var(--font-mono);font-size:11px;letter-spacing:.12em;text-transform:uppercase;color:var(--muted)}.big-num{font-family:var(--font-display);font-size:32px;font-weight:600;line-height:1}.timeline-item{display:flex;gap:14px}.timeline-rail{display:flex;flex-direction:column;align-items:center}.timeline-dot{width:9px;height:9px;border-radius:99px;background:#d8cfbb;margin-top:5px;flex-shrink:0}.timeline-dot.active{background:var(--gold)}.timeline-line{width:1px;flex:1;background:var(--line)}.gate{min-height:100dvh;display:grid;place-items:center;padding:24px 20px}.nav-badge{position:absolute;top:4px;right:calc(50% - 22px);min-width:16px;height:16px;padding:0 4px;border-radius:99px;background:var(--gold);color:#fff;font-family:var(--font-mono);font-size:10px;font-weight:600;line-height:16px;text-align:center}.sidebar .nav-badge{right:10px;top:50%;transform:translateY(-50%)}@keyframes fadeUp{0%{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}.fade-up{animation:fadeUp .25s ease}@media (prefers-reduced-motion: reduce){*{transition:none!important;animation:none!important}}