:root{--bg:#f6f7fb;--surface:#fff;--ink:#1d2330;--muted:#6b7385;--line:#e4e7ef;--hover:#eef1f7;--accent:#3b5bdb;--accent-soft:#e8edff;--good:#2b8a3e;--good-soft:#e6f6ea;--warn:#c2410c;--warn-soft:#fff1e6;--radius:14px;--shadow:0 1px 2px #141c300f, 0 8px 24px #141c3014;--page-shadow:0 1px 3px #141c301a, 0 6px 20px #141c3014;--f:-apple-system, "SF Pro Text", Inter, "IBM Plex Sans Arabic", system-ui, sans-serif;--f-board:"Patrick Hand", "IBM Plex Sans Arabic", sans-serif;--safe-b:env(safe-area-inset-bottom,0px);--lightningcss-light:initial;--lightningcss-dark: ;color-scheme:light}*{box-sizing:border-box;-webkit-tap-highlight-color:transparent}[hidden]{display:none!important}html,body{background:var(--bg);height:100%;color:var(--ink);font:16px/1.45 var(--f);-webkit-font-smoothing:antialiased;margin:0}body{padding:env(safe-area-inset-top,0) env(safe-area-inset-right,0) 0 env(safe-area-inset-left,0)}button,input,select{font:inherit;color:inherit}button{cursor:pointer;touch-action:manipulation;background:0 0;border:0}button:disabled{opacity:.4;cursor:default}:focus-visible{outline:3px solid var(--accent);outline-offset:2px}svg{flex:none}.grow{flex:1}.muted{color:var(--muted);margin:0}.error{color:#c92a2a;margin:0;font-weight:600}.link{color:var(--accent);padding:10px;font-weight:600}.btn{background:var(--surface);min-height:44px;box-shadow:inset 0 0 0 1px var(--line);border-radius:12px;justify-content:center;align-items:center;gap:8px;padding:0 16px;font-weight:600;display:inline-flex}.btn:hover{background:var(--hover)}.btn.primary{background:var(--accent);color:#fff;box-shadow:none}.btn.primary:hover{background:#364fc7}.btn.good{background:var(--good);color:#fff;box-shadow:none}.btn.wide{width:100%;min-height:50px;font-size:17px}.tb{min-width:44px;min-height:44px;color:var(--ink);border-radius:10px;justify-content:center;align-items:center;gap:6px;padding:0 10px;font-weight:600;display:inline-flex}.tb:hover{background:var(--hover)}.tb[aria-pressed=true]{background:var(--accent-soft);color:var(--accent)}.app-mark{background:var(--accent);color:#fff;border-radius:16px;place-items:center;width:56px;height:56px;display:grid}.app-mark.small{border-radius:9px;width:30px;height:30px}.welcome{place-items:center;min-height:100dvh;padding:24px;display:grid}.signin{background:var(--surface);width:min(420px,100%);box-shadow:var(--shadow);text-align:center;border-radius:22px;justify-items:center;gap:14px;padding:32px 28px 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20px;display:grid}.cover{text-align:start;gap:10px;padding:0;display:grid;position:relative}.cover-art{aspect-ratio:1000/1300;background:var(--surface);box-shadow:var(--page-shadow);border-radius:6px 14px 14px 6px;transition:transform .15s;position:relative;overflow:hidden}.cover:active .cover-art{transform:scale(.97)}.cover-art .spine{background:#0000001f;width:14px;position:absolute;inset-block:0;inset-inline-start:0}.cover-art.book{color:#fff;align-content:center;justify-items:center;gap:10px;padding:18px 18px 18px 32px;display:grid}.cover-art.book .sample{font:30px/1.1 var(--f-board);text-align:center;opacity:.95}.cover-art.book .topic-name{letter-spacing:.06em;text-transform:uppercase;opacity:.85;text-align:center;font-size:13px;font-weight:700}.cover-art svg.preview{width:100%;height:100%;position:absolute;inset:0}.cover-meta{gap:2px;padding:0 2px;display:grid}.cover-meta b{font-weight:600}.cover-meta small{color:var(--muted);font-size:13px}.progress{background:var(--line);border-radius:99px;height:4px;margin-top:4px;overflow:hidden}.progress i{background:var(--good);height:100%;display:block}.cover.new .cover-art{box-shadow:none;border:2px dashed var(--line);color:var(--muted);background:0 0;border-radius:14px;align-content:center;place-items:center;gap:8px;font-weight:600;display:grid}.cover .more{top:6px;z-index:2;background:#ffffffe6;border-radius:50%;position:absolute;inset-inline-end:6px}.editor{grid-template-rows:auto auto 1fr;height:100dvh;display:grid}.bar{background:var(--surface);border-bottom:1px solid var(--line);align-items:center;gap:8px;padding:6px 10px;display:flex}.back{color:var(--accent)}.nb-title{min-width:0;display:grid}.nb-title input{background:0 0;border:0;border-radius:8px;width:min(40vw,360px);min-width:0;padding:2px 6px;font-size:17px;font-weight:700}.nb-title input:focus{background:var(--hover);outline:none}.nb-title input[readonly]{pointer-events:none}.nb-title small{color:var(--muted);padding:0 6px;font-size:12px}.right{gap:2px;display:flex}.tutor-btn{background:var(--accent);color:#fff;padding:0 14px}.tutor-btn:hover,.tutor-btn[aria-pressed=true]{color:#fff;background:#364fc7}.toolbar{background:var(--surface);border-bottom:1px solid var(--line);flex-wrap:wrap;justify-content:center;align-items:center;gap:4px;padding:4px 10px;display:flex}.sep{background:var(--line);width:1px;height:24px;margin:0 6px}.swatches,.sizes{gap:2px;display:flex}.swatch{border-radius:50%;place-items:center;width:44px;height:44px;display:grid}.swatch i{border-radius:50%;width:22px;height:22px;display:block;box-shadow:inset 0 0 0 1px #0000001f}.swatch[aria-pressed=true] i{box-shadow:0 0 0 2px var(--surface), 0 0 0 4px var(--accent)}.size{border-radius:10px;place-items:center;width:44px;height:44px;display:grid}.size i{background:var(--ink);border-radius:50%;display:block}.size[aria-pressed=true]{background:var(--accent-soft)}.size[aria-pressed=true] i{background:var(--accent)}.work{min-height:0;display:flex;position:relative}.scroller{-webkit-overflow-scrolling:touch;overscroll-behavior:contain;flex:1;overflow:auto}.pages{padding:24px 0 calc(80px + var(--safe-b));gap:26px;width:min(860px,100% - 32px);margin:0 auto;display:grid}.page{box-shadow:var(--page-shadow);background:#fff;border-radius:4px;position:relative}.page svg.board{touch-action:none;-webkit-user-select:none;user-select:none;-webkit-touch-callout:none;width:100%;height:auto;display:block}.page svg.board text{font-family:var(--f-board)}.page-no{bottom:-20px;color:var(--muted);font-size:12px;position:absolute;inset-inline-end:4px}.page .solved-badge{top:12px;background:var(--good-soft);color:var(--good);border-radius:99px;align-items:center;gap:4px;padding:4px 10px;font-size:13px;font-weight:600;display:inline-flex;position:absolute;inset-inline-end:12px}.add-page{justify-self:center}.erasing svg.board{cursor:cell}.thumbs{background:var(--surface);border-inline-end:1px solid var(--line);flex:none;align-content:start;gap:14px;width:132px;padding:12px;display:grid;overflow:auto}.thumb{color:var(--muted);justify-items:center;gap:4px;padding:0;font-size:12px;display:grid}.thumb svg{width:100%;height:auto;box-shadow:0 0 0 1px var(--line);background:#fff;border-radius:3px}.thumb[aria-current=true] svg{box-shadow:0 0 0 2px var(--accent)}.thumb[aria-current=true]{color:var(--accent);font-weight:600}.panel{width:380px;padding:14px 14px calc(14px + var(--safe-b));background:var(--surface);border-inline-start:1px solid var(--line);flex-direction:column;flex:none;gap:12px;display:flex;overflow:auto}.panel.wide{width:min(560px,48%)}.panel-top{align-items:center;gap:8px;display:flex}.panel-top h2{margin:0;font-size:17px}.panel-mark{background:var(--accent-soft);width:30px;height:30px;color:var(--accent);border-radius:9px;place-items:center;display:grid}.panel-problem{background:var(--bg);border-radius:10px;margin:0;padding:10px 12px;font-weight:600}.panel-actions{flex-wrap:wrap;gap:8px;display:flex}.panel-actions .btn{white-space:nowrap;flex:auto;padding:0 10px;font-size:15px}.explain-board{box-shadow:inset 0 0 0 1px var(--line);border-radius:10px;flex:none;overflow:hidden}.explain-board svg.board{width:100%;height:auto;display:block}.explain-board svg.board text{font-family:var(--f-board)}.feed{flex:1;align-content:start;gap:8px;display:grid}.msg{background:var(--bg);font:18px/1.35 var(--f-board);border-radius:12px;margin:0;padding:10px 12px}.msg.now{background:var(--accent-soft)}.msg.thinking{color:var(--muted);font:italic 15px var(--f);background:0 0;padding:4px 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button[aria-pressed=true]{background:var(--accent-soft);color:var(--accent)}.sheet{z-index:40;background:#141c3052;place-items:center;padding:16px;display:grid;position:fixed;inset:0}.sheet-card{background:var(--surface);width:min(440px,100%);box-shadow:var(--shadow);border-radius:20px;padding:14px}.sheet-top{align-items:center;padding:0 4px 8px;display:flex}.sheet-top h2{margin:0;font-size:19px}.list{gap:2px;display:grid}.row{text-align:start;min-height:50px;color:var(--ink);border-radius:12px;align-items:center;gap:12px;padding:0 12px;font-weight:600;text-decoration:none;display:flex}.row:hover{background:var(--hover)}@media (width<=900px){.library{grid-template-columns:1fr}.side{border-inline-end:0;border-bottom:1px solid var(--line);flex-flow:wrap;align-items:center;height:auto;padding:10px 12px;position:static}.wordmark{padding:0 8px 0 0}.side-nav{display:flex}.side>.grow,.me{display:none}.panel{z-index:25;inset-inline:0;border-inline-start:0;border-top:1px solid var(--line);border-radius:20px 20px 0 0;max-height:62dvh;position:fixed;bottom:0;box-shadow:0 -10px 30px #141c3024;width:auto!important}.thumbs{z-index:24;top:108px;bottom:0;box-shadow:var(--shadow);position:fixed;inset-inline-start:0}}@media (width<=640px){.nb-title input{width:40vw}.back span,.tutor-btn span:not([aria-hidden]){display:none}}@media (prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}}