:root{color-scheme:light;--bg: oklch(.985 0 0);--surface: oklch(1 0 0);--surface-2: oklch(.965 .008 330);--ink: oklch(.19 .025 330);--muted: oklch(.46 .025 330);--faint: oklch(.66 .018 330);--primary: oklch(.36 .147 340);--primary-soft: oklch(.94 .035 340);--accent: oklch(.65 .135 205);--accent-soft: oklch(.94 .035 205);--success: oklch(.57 .13 150);--border: oklch(.9 .012 330);--border-strong: oklch(.78 .025 330);--topbar: 68px;--rail: 220px;--index: 390px;--radius: 8px;--z-sticky: 10;font-family:Inter,SF Pro Text,PingFang SC,Microsoft YaHei,system-ui,sans-serif}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--bg);color:var(--ink);overflow:hidden}body.modal-open{overflow:hidden}button,input{font:inherit}button{color:inherit}button:focus-visible,input:focus-visible,a:focus-visible{outline:2px solid var(--accent);outline-offset:2px}.topbar{height:var(--topbar);display:grid;grid-template-columns:var(--rail) minmax(300px,620px) 1fr;align-items:center;gap:24px;padding:0 20px;background:var(--surface);border-bottom:1px solid var(--border);position:relative;z-index:var(--z-sticky)}.brand{color:var(--ink);display:flex;align-items:center;gap:10px;text-decoration:none;min-width:0}.brand-mark{display:grid;place-items:center;width:34px;height:34px;border-radius:7px;background:var(--primary);color:#fff;font-weight:800;font-size:13px}.brand strong,.brand small{display:block;letter-spacing:0;line-height:1.12}.brand strong{font-size:14px}.brand small{color:var(--muted);font-size:11px;margin-top:2px}.search{display:flex;align-items:center;gap:10px;height:40px;padding:0 11px;background:var(--surface-2);border-radius:var(--radius);color:var(--muted)}.search svg{width:17px}.search input{flex:1;min-width:0;border:0;outline:0;background:transparent;color:var(--ink)}.search input::placeholder{color:var(--muted);opacity:1}kbd{border:1px solid var(--border-strong);border-radius:4px;padding:1px 6px;background:var(--surface);font-size:11px}.top-actions{display:flex;justify-content:flex-end;gap:6px}.icon-btn{width:36px;height:36px;display:grid;place-items:center;border:0;border-radius:7px;background:transparent;cursor:pointer;position:relative}.icon-btn:hover{background:var(--surface-2)}.icon-btn svg{width:18px;height:18px}.recall-launch{min-height:36px;display:inline-flex;align-items:center;gap:7px;border:0;border-radius:7px;padding:0 11px;background:var(--primary);color:#fff;font-size:12px;font-weight:650;cursor:pointer}.recall-launch:hover{background:#580045;background:oklch(.31 .14 340)}.recall-launch svg{width:15px;height:15px}[data-tooltip]:after{content:attr(data-tooltip);position:absolute;top:calc(100% + 7px);right:0;z-index:20;background:var(--ink);color:#fff;font-size:11px;white-space:nowrap;padding:5px 7px;border-radius:4px;opacity:0;pointer-events:none;transform:translateY(-3px);transition:.15s ease}[data-tooltip]:hover:after{opacity:1;transform:translateY(0)}.app-shell{height:calc(100vh - var(--topbar));display:grid;grid-template-columns:var(--rail) var(--index) minmax(0,1fr)}.chapter-rail,.concept-index,.reader{min-width:0;overflow-y:auto}.chapter-rail{padding:22px 14px 14px;border-right:1px solid var(--border);background:var(--surface-2);display:flex;flex-direction:column}.rail-heading{display:flex;align-items:baseline;justify-content:space-between;color:var(--muted);font-size:12px;padding:0 7px}.rail-heading strong{color:var(--ink);font-size:12px}.progress-track{height:4px;background:var(--border);margin:10px 7px 20px;border-radius:2px;overflow:hidden}.progress-track span{display:block;width:0;height:100%;background:var(--success);transform-origin:left center}#chapterNav{display:grid;gap:3px}.chapter-btn{width:100%;border:0;background:transparent;display:grid;grid-template-columns:25px 1fr auto;align-items:center;gap:7px;padding:9px 7px;border-radius:6px;cursor:pointer;text-align:left;color:var(--muted)}.chapter-btn:hover,.chapter-btn.active{background:var(--surface);color:var(--ink)}.chapter-btn.active .chapter-code{background:var(--primary);color:#fff}.chapter-code{width:24px;height:24px;display:grid;place-items:center;border-radius:5px;background:var(--border);font-size:11px;font-weight:800}.chapter-name{font-size:12px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.chapter-count{font:10px ui-monospace,SFMono-Regular,monospace;color:var(--faint)}.rail-note{display:flex;gap:9px;margin:24px 7px 0;padding-top:16px;border-top:1px solid var(--border);color:var(--muted)}.rail-note svg{width:16px;flex:none;color:var(--primary)}.rail-note p{margin:0;font-size:11px;line-height:1.6}.rail-copyright{margin-top:auto;padding:18px 7px 2px;color:var(--faint);font:10px ui-monospace,SFMono-Regular,Menlo,monospace}.concept-index{border-right:1px solid var(--border);background:var(--surface)}.index-head{position:sticky;top:0;z-index:4;background:color-mix(in oklch,var(--surface) 94%,transparent);-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px);padding:22px 20px 14px;border-bottom:1px solid var(--border)}.index-head p{margin:0 0 4px;color:var(--primary);font:700 10px ui-monospace,SFMono-Regular,monospace;text-transform:uppercase}.index-head h1{margin:0 0 16px;font-size:20px;letter-spacing:0}.segmented{display:grid;grid-template-columns:repeat(3,1fr);padding:3px;background:var(--surface-2);border-radius:7px}.segmented button{border:0;border-radius:5px;background:transparent;padding:6px;color:var(--muted);font-size:12px;cursor:pointer}.segmented button.active{background:var(--surface);color:var(--ink);font-weight:650;box-shadow:0 1px 3px #1616161f}.concept-list{padding:8px}.concept-row{width:100%;display:grid;grid-template-columns:34px minmax(0,1fr) 24px;gap:10px;align-items:start;border:0;background:transparent;padding:11px 10px;border-radius:7px;text-align:left;cursor:pointer}.concept-row:hover{background:var(--surface-2)}.concept-row.active{background:var(--primary-soft)}.concept-row.active .concept-number{color:var(--primary)}.concept-number{color:var(--faint);font:700 11px ui-monospace,SFMono-Regular,monospace;padding-top:3px}.concept-copy{min-width:0}.concept-copy strong{display:block;font-size:13px;line-height:1.35;overflow-wrap:anywhere}.concept-copy span{display:block;color:var(--muted);font-size:11px;margin-top:3px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.state-dot{width:18px;height:18px;border:1px solid var(--border-strong);border-radius:50%;margin-top:1px}.concept-row.mastered .state-dot{border-color:var(--success);background:var(--success);box-shadow:inset 0 0 0 4px var(--surface)}.empty-state{text-align:center;padding:70px 28px;color:var(--muted)}.empty-state 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28px);overflow-y:auto;border-radius:12px;padding:32px;color:var(--ink);background:var(--surface)}.dialog-close{position:absolute;top:12px;right:12px}.recall-label{color:var(--primary);font:800 11px ui-monospace,SFMono-Regular,monospace;margin:0 0 10px}.recall-dialog h2{font-size:25px;margin:0 36px 10px 0;text-wrap:balance}.recall-dialog>p:not(.recall-label){color:var(--muted);line-height:1.7}.primary-btn{display:inline-flex;align-items:center;gap:8px;border:0;background:var(--primary);color:#fff;padding:9px 12px;border-radius:6px;cursor:pointer}.primary-btn svg{width:16px}.recall-actions{display:flex;flex-wrap:wrap;gap:8px;margin-top:18px}.secondary-btn,.text-btn{display:inline-flex;align-items:center;gap:7px;border-radius:6px;cursor:pointer;font-size:12px}.secondary-btn{border:1px solid var(--border-strong);background:var(--surface);padding:8px 11px}.secondary-btn:hover{background:var(--surface-2)}.secondary-btn svg,.text-btn svg{width:15px}.text-btn{margin-top:16px;border:0;background:transparent;padding:5px 0;color:var(--primary)}.text-btn:hover{color:var(--ink)}#recallAnswer{margin-top:20px;padding-top:20px;border-top:1px solid var(--border);line-height:1.7;font-size:14px}.recall-translation{padding:9px 11px;border-radius:6px;background:var(--accent-soft);color:#003b40;color:oklch(.32 .075 205)}.mobile-only{display:none}@media(max-width:1100px){:root{--index: 330px;--rail: 190px}.topbar{grid-template-columns:var(--rail) minmax(260px,520px) 1fr;gap:14px}.reader{padding-inline:32px}.zend-layout{grid-template-columns:1fr}.zend-layout figure{position:static;max-width:680px}}@media(max-width:820px){body{overflow:auto}.topbar{grid-template-columns:auto minmax(0,1fr) auto;height:62px;padding:0 12px}.brand small{display:none}.brand strong{font-size:12px}.search{height:38px}.search kbd{display:none}.recall-launch{width:36px;padding:0;justify-content:center}.recall-launch span:last-child{display:none}.mobile-only{display:grid}.app-shell{height:auto;min-height:calc(100vh - 62px);display:block}.chapter-rail{display:none;position:fixed;inset:62px 0 0;z-index:9;width:min(300px,88vw);box-shadow:8px 0 16px #16161629}.chapter-rail.open{display:flex}.concept-index{border-right:0;overflow:visible}.index-head{padding:16px 14px 12px}.concept-list{padding:6px;max-height:42vh;overflow-y:auto;border-bottom:1px solid var(--border)}.reader{overflow:visible;padding:30px 18px 64px}.reader h2{font-size:26px}}@media(prefers-reduced-motion:reduce){*,*:before,*:after{scroll-behavior:auto!important;transition-duration:.001ms!important;animation-duration:.001ms!important}}