:root,[data-theme=light]{--bg:#f4f6fa;--surface:#fff;--surface-alt:#eef2f8;--border:#e2e8f0;--text:#0f172a;--text-muted:#64748b;--sidebar-bg:#0a1830;--sidebar-text:#94a3b8;--sidebar-text-active:#fff;--sidebar-active-bg:#3b82f62e;--accent:#2563eb;--accent-dark:#1d4ed8;--accent-soft:#eaf1ff;--success:#16a34a;--success-soft:#ecfdf3;--warning:#b45309;--warning-soft:#fff7e6;--danger:#dc2626;--danger-soft:#fef2f2;--radius:14px;--radius-sm:8px;--shadow-sm:0 1px 2px #1018280d;--shadow-md:0 4px 20px #10182814}[data-theme=dark]{--bg:#0a0f1c;--surface:#111827;--surface-alt:#0f1622;--border:#1f2937;--text:#e8ecf3;--text-muted:#8b96a8;--sidebar-bg:#060a14;--sidebar-text:#7e8aa0;--sidebar-text-active:#fff;--sidebar-active-bg:#3b82f638;--accent:#3b82f6;--accent-dark:#2563eb;--accent-soft:#3b82f624;--success:#22c55e;--success-soft:#22c55e1f;--warning:#f59e0b;--warning-soft:#f59e0b24;--danger:#f87171;--danger-soft:#f871711f;--shadow-sm:0 1px 2px #0000004d;--shadow-md:0 8px 28px #00000073}*{box-sizing:border-box}body{background:var(--bg);color:var(--text);margin:0;font-family:-apple-system,system-ui,Segoe UI,Helvetica,Arial,sans-serif}a{color:inherit}.app-shell{background:var(--bg);min-height:100vh;color:var(--text);display:flex}.sidebar{background:var(--sidebar-bg);flex-direction:column;flex-shrink:0;width:240px;height:100vh;padding:24px 16px;display:flex;position:sticky;top:0}.sidebar-brand-row{justify-content:space-between;align-items:center;margin-bottom:28px;padding:0 10px;display:flex}.sidebar-brand{color:#fff;letter-spacing:-.2px;font-size:17px;font-weight:700}.sidebar-close-btn{color:#fff;cursor:pointer;background:#ffffff0f;border:none;border-radius:8px;flex-shrink:0;justify-content:center;align-items:center;width:32px;height:32px;display:none}.sidebar-nav{flex-direction:column;gap:4px;display:flex}.sidebar-link{color:var(--sidebar-text);cursor:pointer;text-align:left;background:0 0;border:none;border-radius:10px;align-items:center;gap:10px;width:100%;padding:10px 12px;font-size:14px;font-weight:500;text-decoration:none;display:flex}.sidebar-link:hover{color:#fff;background:#ffffff0d}.sidebar-link.active{background:var(--sidebar-active-bg);color:var(--sidebar-text-active)}.sidebar-link svg{flex-shrink:0}.sidebar-footer{border-top:none;padding-top:0}.main-area{flex:1;min-width:0}.topbar{border-bottom:1px solid var(--border);background:var(--surface);justify-content:space-between;align-items:center;padding:16px 28px;display:flex}.topbar-left{align-items:center;gap:14px;min-width:0;display:flex}.topbar-greeting{white-space:nowrap;text-overflow:ellipsis;font-size:16px;font-weight:600;overflow:hidden}.topbar-right{flex-shrink:0;align-items:center;gap:14px;display:flex}.topbar-email{color:var(--text-muted);font-size:13px}.theme-toggle{border:1px solid var(--border);background:var(--surface-alt);width:38px;height:38px;color:var(--text);cursor:pointer;border-radius:10px;justify-content:center;align-items:center;display:flex}.theme-toggle:hover{background:var(--accent-soft);color:var(--accent)}.hamburger-btn{border:1px solid var(--border);background:var(--surface-alt);width:38px;height:38px;color:var(--text);cursor:pointer;border-radius:10px;flex-shrink:0;justify-content:center;align-items:center;display:none}.hamburger-btn:hover{background:var(--accent-soft);color:var(--accent)}.sidebar-overlay{display:none}.page-body{max-width:1100px;margin:0 auto;padding:28px 32px 48px}.full-loading{min-height:100vh;color:var(--text-muted);background:var(--bg);justify-content:center;align-items:center;font-size:15px;display:flex}.stat-grid{grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:16px;margin-bottom:28px;display:grid}.stat-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow-sm);padding:18px 20px}.stat-label{color:var(--text-muted);justify-content:space-between;align-items:center;font-size:13px;font-weight:500;display:flex}.stat-value{color:var(--text);margin-top:8px;font-size:28px;font-weight:700}.page-heading{color:var(--text);margin:0 0 18px;font-size:20px;font-weight:700}.page-heading-row{justify-content:space-between;align-items:baseline;margin-bottom:18px;display:flex}.link-muted{color:var(--accent);cursor:pointer;font-size:13px;font-weight:600;text-decoration:none}.course-grid{grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:20px;display:grid}.course-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow-sm);flex-direction:column;display:flex;overflow:hidden}.course-thumb{object-fit:cover;background:var(--accent-soft);width:100%;height:150px;display:block}.course-card-body{flex-direction:column;flex:1;gap:10px;padding:18px 20px;display:flex}.course-title{color:var(--text);margin:0;font-size:16px;font-weight:600}.course-desc{color:var(--text-muted);flex:1;margin:0;font-size:13px;line-height:1.55}.continue-row{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);cursor:pointer;align-items:center;gap:16px;margin-bottom:12px;padding:16px 18px;display:flex}.continue-thumb{object-fit:cover;background:var(--accent-soft);border-radius:8px;flex-shrink:0;width:76px;height:54px}.continue-body{flex:1;min-width:0}.continue-title{color:var(--text);margin:0 0 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0}.btn-outline:hover{border-color:var(--accent);color:var(--accent)}.btn:disabled{opacity:.6;cursor:not-allowed}.badge{text-align:center;border-radius:10px;justify-content:center;align-items:center;gap:6px;padding:10px 14px;font-size:13px;font-weight:600;display:flex}.badge-warning{background:var(--warning-soft);color:var(--warning)}.badge-muted{background:var(--surface-alt);color:var(--text-muted)}.field{border:1px solid var(--border);background:var(--bg);width:100%;color:var(--text);border-radius:10px;outline:none;padding:12px 14px;font-size:14px}.field:focus{border-color:var(--accent)}.field-error{color:var(--danger);margin:6px 0 0;font-size:13px}.text-link{text-align:center;color:var(--text-muted);cursor:pointer;margin-top:10px;font-size:13px}.text-link:hover{color:var(--accent)}.empty-state{color:var(--text-muted);background:var(--surface);border:1px dashed var(--border);border-radius:var(--radius);text-align:center;padding:32px;font-size:14px}.hero-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow-sm);margin-bottom:24px;padding:24px}.section-card{border:1px solid var(--border);border-radius:var(--radius);background:var(--surface);box-shadow:var(--shadow-sm);margin-bottom:12px;overflow:hidden}.section-header{cursor:pointer;background:var(--sidebar-bg);color:#fff;justify-content:space-between;align-items:center;padding:16px 20px;display:flex}.section-left{align-items:center;gap:14px;display:flex}.section-icon{color:#fff;background:var(--accent);border-radius:8px;flex-shrink:0;justify-content:center;align-items:center;width:36px;height:36px;font-size:12px;font-weight:700;display:flex}.section-label{font-size:15px;font-weight:700}.section-sub{color:#9fb2d9;margin-top:2px;font-size:12px}.lesson-row{border-bottom:1px solid var(--border);cursor:pointer;background:var(--surface);justify-content:space-between;align-items:center;padding:14px 20px;display:flex}.lesson-row:last-child{border-bottom:none}.lesson-row:hover{background:var(--surface-alt)}.lesson-row.current{background:var(--accent-soft)}.lesson-left{flex:1;align-items:center;gap:10px;min-width:0;display:flex}.lesson-check{border:2px solid var(--border);color:#fff;border-radius:999px;flex-shrink:0;justify-content:center;align-items:center;width:20px;height:20px;font-size:11px;display:flex}.lesson-check.done{background:var(--success);border-color:var(--success)}.lesson-name{color:var(--text);white-space:nowrap;text-overflow:ellipsis;font-size:14px;overflow:hidden}.tag{border-radius:999px;flex-shrink:0;padding:2px 8px;font-size:11px;font-weight:600}.player-shell{background:var(--bg);min-height:100vh;display:flex}.player-topbar{background:var(--sidebar-bg);justify-content:space-between;align-items:center;padding:14px 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var(--border);border-radius:var(--radius);align-items:center;gap:14px;margin-bottom:10px;padding:14px 16px;display:flex}.admin-row-thumb{object-fit:cover;background:var(--accent-soft);border-radius:8px;flex-shrink:0;width:56px;height:42px}.admin-row-body{flex:1;min-width:0}.admin-row-title{color:var(--text);margin:0 0 4px;font-size:14px;font-weight:600}.admin-row-meta{color:var(--text-muted);font-size:12px}.admin-row-actions{flex-shrink:0;align-items:center;gap:6px;display:flex}.icon-btn{border:1px solid var(--border);background:var(--surface-alt);width:32px;height:32px;color:var(--text-muted);cursor:pointer;border-radius:8px;justify-content:center;align-items:center;display:flex}.icon-btn:hover{color:var(--accent);border-color:var(--accent)}.icon-btn.danger:hover{color:var(--danger);border-color:var(--danger)}.chip{border-radius:999px;flex-shrink:0;padding:3px 9px;font-size:11px;font-weight:600}.chip-locked{background:var(--surface-alt);color:var(--text-muted)}.chip-code{background:var(--accent-soft);color:var(--accent)}.admin-tabs{border-bottom:1px solid var(--border);gap:6px;margin-bottom:20px;display:flex}.admin-tab{color:var(--text-muted);cursor:pointer;background:0 0;border:none;border-bottom:2px solid #0000;padding:10px 16px;font-size:14px;font-weight:600}.admin-tab.active{color:var(--accent);border-bottom-color:var(--accent)}.sidebar-divider{background:#ffffff14;height:1px;margin:14px 4px}.topbar-avatar-btn{border:1px solid var(--border);background:var(--accent-soft);width:38px;height:38px;color:var(--accent);cursor:pointer;border-radius:999px;flex-shrink:0;justify-content:center;align-items:center;padding:0;font-size:13px;font-weight:700;display:flex;overflow:hidden}.topbar-avatar-btn img{object-fit:cover;width:100%;height:100%}.settings-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow-sm);max-width:560px;margin-bottom:20px;padding:24px}.avatar-row{align-items:center;gap:18px;margin-bottom:22px;display:flex}.avatar-preview{border:1px solid var(--border);background:var(--accent-soft);width:72px;height:72px;color:var(--accent);border-radius:999px;flex-shrink:0;justify-content:center;align-items:center;font-size:24px;font-weight:700;display:flex;overflow:hidden}.avatar-preview img{object-fit:cover;width:100%;height:100%}.field-locked{border:1px solid var(--border);background:var(--surface-alt);width:100%;color:var(--text-muted);border-radius:10px;padding:12px 14px;font-size:14px}.save-confirm{color:var(--success);margin:0 0 0 4px;font-size:13px}@media (width<=860px){.hamburger-btn{display:flex}.sidebar{z-index:100;box-shadow:var(--shadow-md);transition:transform .25s;display:flex;position:fixed;top:0;left:0;transform:translate(-100%)}.sidebar.mobile-open{transform:translate(0)}.sidebar-close-btn{display:flex}.sidebar-overlay.mobile-open{z-index:99;background:#00000080;display:block;position:fixed;inset:0}.player-sidebar{display:none}.page-body{padding:20px}.topbar{padding:14px 16px}.topbar-email{display:none}}@media (width<=640px){.form-grid{grid-template-columns:1fr}}.upload-target{cursor:pointer;justify-content:center;align-items:center;display:flex;position:relative;overflow:hidden}.upload-target img{object-fit:cover;width:100%;height:100%}.upload-placeholder{color:var(--accent);text-align:center;padding:0 8px;font-size:12px;font-weight:600}.upload-overlay{color:#fff;text-align:center;opacity:0;background:#0a1830a6;justify-content:center;align-items:center;font-size:11px;font-weight:600;transition:opacity .15s;display:flex;position:absolute;inset:0}.upload-target:hover .upload-overlay,.upload-target:active .upload-overlay{opacity:1}.course-thumb-upload{border-radius:var(--radius);background:var(--accent-soft);border:1px dashed var(--border);width:100%;height:150px}.settings-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);max-width:560px;padding:24px}.avatar-row{align-items:center;margin-bottom:20px;display:flex}.avatar-preview{object-fit:cover;border:1px solid var(--border);border-radius:999px;width:72px;height:72px}.avatar-preview-fallback{background:var(--accent);color:#fff;border-radius:999px;flex-shrink:0;justify-content:center;align-items:center;width:72px;height:72px;font-size:26px;font-weight:700;display:flex}.form-hint{color:var(--text-muted);margin:6px 0 0;font-size:12px}.field-locked{border:1px solid var(--border);background:var(--surface-alt);color:var(--text-muted);border-radius:10px;padding:12px 14px;font-size:14px}.save-confirm{color:var(--success);margin-left:4px;font-size:14px;font-weight:600}.modal-overlay{z-index:200;background:#0a0f1c99;justify-content:center;align-items:center;padding:20px;display:flex;position:fixed;inset:0}.modal-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);width:100%;max-width:420px;box-shadow:var(--shadow-md);max-height:90vh;padding:24px;overflow-y:auto}.player-topbar .btn-outline{color:#fff;border-color:#ffffff4d}.player-topbar .btn-outline:hover{color:var(--accent);border-color:var(--accent)}.note-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);cursor:pointer;margin-bottom:12px;padding:16px 18px}.note-card:hover{border-color:var(--accent)}.note-card-top{justify-content:space-between;align-items:flex-start;gap:10px;margin-bottom:6px;display:flex}.note-card-title{color:var(--text);margin:0;font-size:15px;font-weight:700}.note-card-actions{flex-shrink:0;gap:6px;display:flex}.note-card-content{color:var(--text-muted);-webkit-line-clamp:3;-webkit-box-orient:vertical;margin:0 0 8px;font-size:13px;line-height:1.5;display:-webkit-box;overflow:hidden}.note-card-meta{color:var(--text-muted);align-items:center;gap:8px;font-size:12px;display:flex}.discussion-composer{flex-direction:column;gap:10px;margin-bottom:24px;display:flex}.discussion-post{border-bottom:1px solid var(--border);gap:12px;padding:14px 0;display:flex}.discussion-post:last-child{border-bottom:none}.avatar-mini{object-fit:cover;border:1px solid var(--border);border-radius:999px;flex-shrink:0;width:34px;height:34px}.avatar-mini-fallback{background:var(--accent);color:#fff;border-radius:999px;flex-shrink:0;justify-content:center;align-items:center;width:34px;height:34px;font-size:13px;font-weight:700;display:flex}.discussion-post-body{flex:1;min-width:0}.discussion-post-header{align-items:baseline;gap:8px;margin-bottom:4px;display:flex}.discussion-post-author{color:var(--text);font-size:13px;font-weight:700}.discussion-post-time{color:var(--text-muted);font-size:11px}.discussion-post-text{color:var(--text);white-space:pre-wrap;word-break:break-word;font-size:14px;line-height:1.55}.discussion-replies-wrap{border-left:2px solid var(--border);margin-top:12px;padding-left:16px}.discussion-reply-row{gap:10px;margin-bottom:12px;display:flex}.discussion-reply-row:last-child{margin-bottom:0}.discussion-reply-composer{max-width:480px;margin-top:10px}.discussion-post.pinned{border-color:var(--accent);background:var(--accent-soft)}.chip-pinned{background:var(--warning-soft);color:var(--warning);margin-right:6px}.admin-toggle-row{align-items:center;gap:10px;margin-bottom:20px;display:flex}.switch{flex-shrink:0;width:40px;height:22px;display:inline-block;position:relative}.switch input{opacity:0;width:0;height:0}.switch-slider{cursor:pointer;background:var(--surface-alt);border:1px solid var(--border);border-radius:999px;transition:all .15s;position:absolute;inset:0}.switch-slider:before{content:"";width:16px;height:16px;box-shadow:var(--shadow-sm);background:#fff;border-radius:999px;transition:all .15s;position:absolute;bottom:2px;left:2px}.switch input:checked+.switch-slider{background:var(--accent);border-color:var(--accent)}.switch input:checked+.switch-slider:before{transform:translate(18px)}.switch input:disabled+.switch-slider{opacity:.6;cursor:not-allowed}