:root{color-scheme:light;--bg: #f4f7ff;--bg-2: #edf2ff;--card: rgba(255, 255, 255, .82);--card-solid: #ffffff;--line: #e4e9f5;--line-strong: #d5dcf0;--text: #0f172a;--muted: #64748b;--primary: #5b5ce2;--primary-hover: #4547d9;--primary-soft: rgba(91, 92, 226, .12);--success: #16a34a;--warning: #d97706;--danger: #dc2626;--shadow: 0 24px 70px rgba(15, 23, 42, .12);--radius: 22px}*{box-sizing:border-box}html,body,#app{min-height:100%}body{margin:0;font-family:Inter,-apple-system,BlinkMacSystemFont,Segoe UI,PingFang SC,Hiragino Sans GB,Microsoft YaHei,sans-serif;background:radial-gradient(circle at 14% 10%,rgba(91,92,226,.16),transparent 26%),radial-gradient(circle at 86% 12%,rgba(14,165,233,.12),transparent 24%),radial-gradient(circle at 50% 92%,rgba(34,197,94,.08),transparent 22%),linear-gradient(180deg,#f9fbff 0%,var(--bg) 100%);color:var(--text);overflow-x:hidden}body:before{content:"";position:fixed;inset:0;pointer-events:none;background-image:linear-gradient(rgba(255,255,255,.22) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.22) 1px,transparent 1px);background-size:42px 42px;-webkit-mask-image:linear-gradient(180deg,rgba(0,0,0,.18),transparent 40%);mask-image:linear-gradient(180deg,rgba(0,0,0,.18),transparent 40%);opacity:.45}a{color:inherit}button,input,textarea,select{font:inherit}button{border:1px solid transparent;border-radius:14px;background:linear-gradient(180deg,#6366f1 0%,var(--primary) 100%);color:#fff;padding:10px 14px;cursor:pointer;transition:transform .15s ease,background .2s ease,box-shadow .2s ease,border-color .2s ease;box-shadow:0 14px 32px #5b5ce233}button:hover{background:linear-gradient(180deg,#5254e9 0%,var(--primary-hover) 100%);transform:translateY(-1px)}button:disabled{opacity:.65;cursor:not-allowed;transform:none}button.btn-surface{background:var(--card-solid, #ffffff);color:var(--text);border:1px solid var(--line);box-shadow:none}button.btn-surface:hover:not(:disabled){background:#f8fafc;border-color:var(--line-strong);color:var(--text);transform:none}button.btn-surface:focus-visible{outline:none;border-color:#5b5ce273;box-shadow:0 0 0 3px #5b5ce226}input,textarea,select{width:100%;border:1px solid var(--line-strong);border-radius:14px;background:#ffffffeb;color:var(--text);padding:11px 14px;outline:none;transition:border-color .2s ease,box-shadow .2s ease,background .2s ease}input::placeholder,textarea::placeholder{color:#94a3b8}input:focus,textarea:focus,select:focus{border-color:#5b5ce280;box-shadow:0 0 0 4px #5b5ce21f;background:#fff}.card{background:var(--card);border:1px solid rgba(228,233,245,.9);border-radius:var(--radius);box-shadow:var(--shadow);-webkit-backdrop-filter:blur(14px);backdrop-filter:blur(14px)}.section-title{margin:0 0 8px;font-size:18px;font-weight:800;letter-spacing:-.03em}.section-desc{margin:0;color:var(--muted);font-size:13px;line-height:1.7}.muted{color:var(--muted)}.small{font-size:12px}.compact-grid{display:grid;gap:12px}.grid-2{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}.grid-3{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}.grid-4{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px}.pill{display:inline-flex;align-items:center;gap:6px;padding:6px 10px;border-radius:999px;background:linear-gradient(180deg,#5b5ce21f,#5b5ce214);color:#4338ca;font-size:12px;font-weight:700}.page-shell{max-width:1180px;margin:0 auto;padding:24px 18px 44px}.page-header{display:flex;align-items:flex-start;justify-content:space-between;gap:14px;margin-bottom:18px}.page-header h1{margin:0;font-size:28px;line-height:1.15;letter-spacing:-.03em}.page-header .lead{margin-top:8px;color:var(--muted);line-height:1.7;max-width:720px}.toolbar{display:flex;align-items:center;gap:10px;flex-wrap:wrap}.toolbar button,.toolbar a,.toolbar .ghost{min-height:42px}.ghost{background:#fff;color:#344054;border:1px solid var(--line);box-shadow:none}.ghost:hover{background:#f8fafc;color:#111827}hr.divider{border:0;border-top:1px solid var(--line);margin:16px 0}.app-root{min-height:100vh;position:relative;isolation:isolate}.auth-mode,.student-mode{display:block}.auth-backdrop,.workspace-backdrop{position:fixed;inset:0;pointer-events:none;z-index:-1}.auth-backdrop{background:radial-gradient(circle at 20% 20%,rgba(91,92,226,.16),transparent 30%),radial-gradient(circle at 80% 18%,rgba(14,165,233,.14),transparent 28%),linear-gradient(180deg,#fafcff,#f4f7ff)}.workspace-backdrop-a{background:radial-gradient(circle at 18% 12%,rgba(91,92,226,.22),transparent 24%),radial-gradient(circle at 82% 16%,rgba(14,165,233,.16),transparent 24%),linear-gradient(180deg,#f7faff,#eef3ff)}.workspace-backdrop-b{background:linear-gradient(135deg,rgba(255,255,255,.32) 0%,transparent 32%,transparent 68%,rgba(255,255,255,.22) 100%)}.app-frame{min-height:100vh;display:grid;grid-template-columns:280px minmax(0,1fr);gap:18px;padding:18px}.side-rail{position:sticky;top:18px;align-self:start;padding:20px;display:grid;gap:16px}.brand-block{display:flex;align-items:center;gap:12px}.brand-mark{width:44px;height:44px;border-radius:14px;display:grid;place-items:center;color:#fff;font-weight:800;background:linear-gradient(135deg,#6366f1,#22c55e);box-shadow:0 16px 30px #5b5ce23d}.brand-name{font-size:16px;font-weight:800;letter-spacing:-.03em}.brand-tag{color:var(--muted);font-size:12px;margin-top:2px}.rail-copy{margin:0;color:var(--muted);font-size:13px;line-height:1.7}.nav-list{display:grid;gap:10px}.nav-item{display:grid;gap:4px;text-decoration:none;border:1px solid var(--line);border-radius:16px;padding:12px 14px;background:#ffffffbd;transition:transform .18s ease,border-color .18s ease,background .18s ease}.nav-item:hover,.nav-item.router-link-active{transform:translateY(-1px);border-color:#5b5ce247;background:#5b5ce214}.nav-item-title{font-size:14px;font-weight:700;color:var(--text)}.nav-item-desc{font-size:12px;color:var(--muted)}.rail-section{display:grid;gap:8px;padding-top:6px;border-top:1px solid var(--line)}.rail-heading{font-size:12px;color:var(--muted);font-weight:700;letter-spacing:.04em;text-transform:uppercase}.rail-link{text-decoration:none;color:#334155;font-size:13px}.rail-link:hover{color:var(--primary)}.rail-footer{display:grid;gap:10px;margin-top:auto;padding-top:6px}.session-chip{display:inline-flex;align-items:center;justify-content:center;padding:8px 12px;border-radius:999px;background:#22c55e1f;color:#166534;font-size:12px;font-weight:700}.rail-button{width:100%}.workspace-shell{min-width:0;display:grid;gap:16px}.workspace-top{padding:22px 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