:root{--cb-bg:#f6f5fb;--cb-surface:#fff;--cb-ink:#1c1b22;--cb-muted:#6b6880;--cb-line:#e4e2ef;--cb-accent:#5b4cff;--cb-accent-ink:#fff;--cb-accent-soft:#ecebff;--cb-ok:#0c8a5f;--cb-warn:#b26a00;--cb-bad:#d1344b;--cb-radius:14px;--cb-shadow:0 1px 2px #14103c0f, 0 8px 24px #14103c0f;--lightningcss-light:initial;--lightningcss-dark: ;color-scheme:light}@media (prefers-color-scheme:dark){:root{--cb-bg:#121118;--cb-surface:#1b1a24;--cb-ink:#ecebf5;--cb-muted:#9a97b0;--cb-line:#2c2a3a;--cb-accent:#7b6dff;--cb-accent-soft:#272352;--cb-shadow:0 1px 2px #0000004d, 0 8px 24px #00000040;--lightningcss-light: ;--lightningcss-dark:initial;color-scheme:dark}}*{box-sizing:border-box}html,body,#root{height:100%;margin:0}body{background:var(--cb-bg);color:var(--cb-ink);font:15px/1.5 Inter,ui-sans-serif,system-ui,-apple-system,Segoe UI,sans-serif}a{color:inherit;text-decoration:none}h1,h2,h3,h4{margin:0 0 8px;line-height:1.2}h1{letter-spacing:-.02em;font-size:26px}h4{text-transform:uppercase;letter-spacing:.06em;color:var(--cb-muted);margin-top:16px;font-size:13px}input,select,textarea{font:inherit;color:inherit;border:1px solid var(--cb-line);background:var(--cb-bg);border-radius:10px;width:100%;padding:9px 11px}input:focus,select:focus,textarea:focus{outline:2px solid var(--cb-accent);outline-offset:-1px}.cb-center{place-items:center;height:100%;display:grid}.cb-muted{color:var(--cb-muted)}.cb-small{font-size:13px}.cb-error{color:var(--cb-bad);font-size:14px}.cb-btn{font:inherit;cursor:pointer;white-space:nowrap;border:1px solid #0000;border-radius:10px;padding:8px 14px;font-weight:600;transition:transform 80ms,background .15s}.cb-btn:active{transform:translateY(1px)}.cb-btn:disabled{opacity:.55;cursor:default}.cb-btn-primary{background:var(--cb-accent);color:var(--cb-accent-ink)}.cb-btn-ghost{border-color:var(--cb-line);color:var(--cb-ink);background:0 0}.cb-btn-ghost:hover{background:var(--cb-accent-soft)}.cb-btn-sm{padding:4px 10px;font-size:13px}.cb-link{font:inherit;color:var(--cb-accent);cursor:pointer;background:0 0;border:0;padding:0;text-decoration:underline}.cb-shell{flex-direction:column;height:100%;display:flex}.cb-topbar{background:var(--cb-surface);border-bottom:1px solid var(--cb-line);justify-content:space-between;align-items:center;padding:10px 20px;display:flex}.cb-topbar-user{align-items:center;gap:12px;display:flex}.cb-brand{letter-spacing:-.02em;align-items:center;gap:8px;font-size:18px;font-weight:800;display:inline-flex}.cb-brand-lg{font-size:26px}.cb-main{flex:1;min-height:0;overflow:auto}.cb-page{max-width:1200px;margin:0 auto;padding:28px 20px}.cb-card{background:var(--cb-surface);border:1px solid var(--cb-line);border-radius:var(--cb-radius);box-shadow:var(--cb-shadow);padding:16px}.cb-section-head{justify-content:space-between;align-items:center;gap:12px;margin-bottom:12px;display:flex;position:relative}.cb-grid{grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:14px;display:grid}.cb-list{flex-direction:column;gap:10px;display:flex}.cb-row,.cb-row-plain{justify-content:space-between;align-items:center;gap:12px;display:flex}.cb-row:hover,.cb-lesson-card:hover{border-color:var(--cb-accent)}.cb-lesson-card-head{justify-content:space-between;gap:8px;display:flex}.cb-dashboard{grid-template-columns:minmax(0,1fr) 340px;gap:28px;display:grid}.cb-dashboard aside{flex-direction:column;gap:12px;display:flex}.cb-student,.cb-form{flex-direction:column;gap:10px;display:flex}.cb-form label{flex-direction:column;gap:4px;font-size:13px;font-weight:600;display:flex}.cb-form .cb-check{flex-direction:row;align-items:center;font-weight:500}.cb-check input{width:auto}.cb-popover{z-index:10;width:min(360px,100vw - 32px);position:absolute;top:100%;right:0}.cb-actions{flex-wrap:wrap;justify-content:flex-end;align-items:center;gap:8px;display:flex}.cb-filter,.cb-topics{flex-wrap:wrap;gap:6px;margin-bottom:14px;display:flex}.cb-pill{font:inherit;border:1px solid var(--cb-line);background:var(--cb-surface);color:var(--cb-ink);cursor:pointer;border-radius:999px;padding:3px 11px;font-size:13px}.cb-pill.on{background:var(--cb-accent-soft);color:var(--cb-accent);border-color:#0000;font-weight:600}.cb-chip{white-space:nowrap;border-radius:999px;padding:2px 9px;font-size:12px;font-weight:600}.cb-chip-ready{background:color-mix(in srgb, var(--cb-ok) 15%, transparent);color:var(--cb-ok)}.cb-chip-pending,.cb-chip-processing{background:color-mix(in srgb, var(--cb-warn) 15%, transparent);color:var(--cb-warn)}.cb-chip-failed{background:color-mix(in srgb, var(--cb-bad) 15%, transparent);color:var(--cb-bad)}.cb-login{background:radial-gradient(60rem 30rem at 10% -10%, var(--cb-accent-soft), transparent), var(--cb-bg);place-items:center;min-height:100%;padding:16px;display:grid}.cb-login-card{flex-direction:column;gap:12px;width:min(400px,100%);padding:28px;display:flex}.cb-login-card label{flex-direction:column;gap:4px;font-size:13px;font-weight:600;display:flex}.cb-demo{color:var(--cb-muted);text-align:center;font-size:13px}.cb-lesson{flex-direction:column;gap:12px;height:100%;padding:16px 20px;display:flex}.cb-lesson-head{flex-wrap:wrap;justify-content:space-between;align-items:flex-start;gap:16px;display:flex}.cb-lesson-body{flex:1;grid-template-columns:minmax(0,1fr) 360px;gap:16px;min-height:0;display:grid}.cb-lesson-boards{flex-direction:column;min-width:0;min-height:480px;display:flex}.cb-tabs{gap:4px;display:flex;overflow-x:auto}.cb-tab{font:inherit;border:1px solid var(--cb-line);background:var(--cb-bg);color:var(--cb-muted);cursor:pointer;white-space:nowrap;border-bottom:0;border-radius:10px 10px 0 0;padding:7px 14px;font-size:14px}.cb-tab.on{background:var(--cb-surface);color:var(--cb-ink);font-weight:600}.cb-board{border:1px solid var(--cb-line);border-radius:0 var(--cb-radius) var(--cb-radius) var(--cb-radius);background:var(--cb-surface);flex-direction:column;flex:1;display:flex;overflow:hidden}.cb-board-toolbar{border-bottom:1px solid var(--cb-line);justify-content:space-between;align-items:center;gap:12px;padding:6px 12px;font-size:13px;display:flex}.cb-opacity{align-items:center;gap:8px;display:flex}.cb-opacity input{width:140px;padding:0}.cb-save{color:var(--cb-muted);margin-left:auto}.cb-save-error{color:var(--cb-bad)}.cb-board-canvas{flex:1;min-height:420px;position:relative}.cb-board-canvas .tl-container{position:absolute;inset:0}.cb-empty{text-align:center;border:1px dashed var(--cb-line);border-radius:var(--cb-radius);background:var(--cb-surface);flex-direction:column;flex:1;justify-content:center;align-items:center;gap:6px;padding:40px 20px;display:flex}.cb-empty p{max-width:440px}.cb-spinner{border:3px solid var(--cb-accent-soft);border-top-color:var(--cb-accent);border-radius:50%;width:34px;height:34px;animation:.9s linear infinite cb-spin}@keyframes cb-spin{to{transform:rotate(360deg)}}.cb-summary{overflow:auto}.cb-summary ul{margin:0;padding-left:18px}.cb-recap{background:var(--cb-accent-soft);border-radius:10px;padding:12px;font-size:16px}.cb-formulas{flex-direction:column;gap:4px;display:flex;overflow-x:auto}.cb-math{pointer-events:all;justify-content:flex-start;align-items:center;display:flex}.cb-math-render .katex-display{margin:0}.cb-math-render{max-width:100%;overflow:hidden}.cb-math-input{resize:none;width:100%;height:100%;font-family:ui-monospace,monospace;font-size:max(12px,.5em)}@media (width<=900px){.cb-dashboard,.cb-lesson-body{grid-template-columns:1fr}.cb-lesson{height:auto}.cb-lesson-boards{min-height:70vh}}