:root,[data-theme=dark]{--color-cyan: #06b6d4;--color-cta-orange: #f97316;--color-cta-orange-hover: #ea580c;--color-background: #0f172a;--color-surface: #1e293b;--color-surface-elevated: #334155;--color-text-primary: #ffffff;--color-text-secondary: #94a3b8;--color-border: rgba(148, 163, 184, .3);--color-border-hover: rgba(6, 182, 212, .5);--gradient-background: radial-gradient(circle at 50% 0%, #1e293b 0%, #0f172a 100%)}*{box-sizing:border-box}body{margin:0;font-family:Inter,system-ui,sans-serif;background:var(--gradient-background);color:var(--color-text-primary)}h1,h2,h3,p{margin:0}a{color:inherit;text-decoration:none}input,select,textarea,button{font:inherit}.app-shell{min-height:100vh;display:grid;grid-template-columns:280px 1fr}.sidebar{border-right:1px solid var(--color-border);padding:20px;background:#0f172ad9;-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);display:flex;flex-direction:column;gap:24px}.brand-block{display:flex;align-items:center;gap:12px}.brand-mark{width:42px;height:42px;border-radius:10px;display:grid;place-items:center;background:var(--color-surface-elevated);color:var(--color-cyan);font-weight:700}.brand-title{font-size:18px;font-weight:700}.brand-subtitle{font-size:12px;color:var(--color-text-secondary)}.nav-stack{display:flex;flex-direction:column;gap:8px}.nav-link{padding:10px 12px;border-radius:10px;color:var(--color-text-secondary);border:1px solid transparent;transition:all .2s}.nav-link:hover{border-color:var(--color-border-hover);color:var(--color-text-primary);background:#33415573}.nav-link-active{background:#06b6d426;border-color:#06b6d459;color:var(--color-cyan)}.sidebar-footer{margin-top:auto;display:grid;gap:8px;font-size:13px;color:var(--color-text-secondary)}.content-area{padding:28px}.page-header{margin-bottom:16px;display:flex;justify-content:space-between;align-items:center;gap:12px}.eyebrow{text-transform:uppercase;letter-spacing:.06em;font-size:12px;color:var(--color-cyan);margin-bottom:4px}.grid-cards{display:grid;gap:12px;grid-template-columns:repeat(auto-fill,minmax(280px,1fr))}.grid-2{display:grid;gap:12px;grid-template-columns:repeat(auto-fit,minmax(280px,1fr))}.panel{background:#1e293bdb;border:1px solid var(--color-border);border-radius:14px;padding:16px;display:grid;gap:10px}.panel.error{border-color:#ef4444;color:#fecaca}.panel.success{border-color:#22c55e;color:#bbf7d0}.form-grid{display:grid;gap:12px;grid-template-columns:repeat(auto-fit,minmax(220px,1fr))}.form-grid .wide{grid-column:1 / -1}label{display:grid;gap:6px;font-size:13px;color:var(--color-text-secondary)}input,select,textarea{border:1px solid var(--color-border);background:#0f172ae6;color:var(--color-text-primary);border-radius:10px;padding:10px}input:focus,select:focus,textarea:focus{outline:none;border-color:var(--color-cyan)}.btn{border:1px solid transparent;border-radius:10px;padding:10px 12px;cursor:pointer;transition:all .2s;white-space:nowrap}.btn:disabled{opacity:.45;cursor:not-allowed}.btn-primary{background:var(--color-cta-orange);color:#fff}.btn-primary:hover:not(:disabled){background:var(--color-cta-orange-hover)}.btn-secondary{background:#33415580;color:#e2e8f0;border-color:var(--color-border)}.btn-block{width:100%}.stack-md{display:grid;gap:12px}.stack-lg{display:grid;gap:16px}.row-between{display:flex;justify-content:space-between;align-items:flex-start;gap:12px}.inline-actions{display:flex;gap:8px;align-items:center}.stat-row{display:flex;justify-content:space-between;color:var(--color-text-secondary);font-size:13px}.lesson-stack{display:grid;gap:10px}.lesson-row{display:flex;justify-content:space-between;align-items:center;gap:10px;border-top:1px solid rgba(148,163,184,.2);padding-top:10px}.lesson-actions{display:flex;gap:8px;align-items:center}.pill{border-radius:999px;padding:4px 10px;font-size:11px;border:1px solid var(--color-border)}.pill-default{color:var(--color-text-secondary)}.pill-success{border-color:#22c55e;color:#22c55e}.pill-warn{border-color:#eab308;color:#fde047}.pill-danger{border-color:#ef4444;color:#fca5a5}.table{width:100%;border-collapse:collapse;font-size:13px}.table th,.table td{text-align:left;padding:10px;border-top:1px solid rgba(148,163,184,.2)}.muted{color:var(--color-text-secondary)}.tiny{font-size:12px}.page-center{min-height:100vh;display:grid;place-items:center;padding:24px}code{background:#0f172acc;border:1px solid var(--color-border);padding:2px 6px;border-radius:8px}@media(max-width:980px){.app-shell{grid-template-columns:1fr}.sidebar{border-right:0;border-bottom:1px solid var(--color-border)}.row-between,.lesson-row,.lesson-actions,.inline-actions,.page-header,.stat-row{flex-direction:column;align-items:flex-start}}