*,*:before,*:after{box-sizing:border-box}:root{--bg: #0d1117;--bg-card: #161b22;--bg-elevated: #21262d;--border: #30363d;--text: #e6edf3;--text-muted: #8b949e;--accent: #58a6ff;--accent-green: #3fb950;--accent-purple: #bc8cff;--danger: #f85149;--radius: 10px;--font-mono: "JetBrains Mono", "Fira Code", "Consolas", monospace}body{margin:0;font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif;background:var(--bg);color:var(--text);line-height:1.6;min-height:100vh}a{color:var(--accent);text-decoration:none}a:hover{text-decoration:underline}.layout{min-height:100vh;display:flex;flex-direction:column}.header{display:flex;align-items:center;gap:24px;padding:0 24px;height:60px;background:var(--bg-card);border-bottom:1px solid var(--border);position:sticky;top:0;z-index:100}.logo{font-family:var(--font-mono);font-weight:700;font-size:1.1rem;color:var(--text);text-decoration:none;white-space:nowrap}.logo-bracket{color:var(--accent-green)}.logo:hover{text-decoration:none}.nav{display:flex;gap:8px;flex:1}.nav a{color:var(--text-muted);padding:6px 12px;border-radius:6px;text-decoration:none;font-size:.95rem}.nav a:hover{color:var(--text);background:var(--bg-elevated);text-decoration:none}.nav a.active{color:var(--text);background:var(--bg-elevated)}.header-auth{display:flex;align-items:center;gap:8px}.user-name{color:var(--text-muted);font-size:.9rem;max-width:120px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.btn{display:inline-flex;align-items:center;justify-content:center;padding:8px 16px;border-radius:8px;font-size:.95rem;font-weight:500;cursor:pointer;border:1px solid transparent;transition:background .15s,border-color .15s;text-decoration:none;font-family:inherit}.btn:hover{text-decoration:none}.btn-primary{background:var(--accent);color:#0d1117;border-color:var(--accent)}.btn-primary:hover{background:#79b8ff}.btn-outline{background:transparent;color:var(--text);border-color:var(--border)}.btn-outline:hover{border-color:var(--text-muted);background:var(--bg-elevated)}.btn-ghost{background:transparent;color:var(--text-muted);border:none}.btn-ghost:hover{color:var(--text);background:var(--bg-elevated)}.btn-lg{padding:12px 24px;font-size:1rem}.btn-full{width:100%}.btn:disabled{opacity:.6;cursor:not-allowed}.main{flex:1;max-width:960px;width:100%;margin:0 auto;padding:32px 24px 64px}.footer{text-align:center;padding:24px;color:var(--text-muted);font-size:.85rem;border-top:1px solid var(--border)}.hero{text-align:center;padding:48px 0 64px}.hero-badge{display:inline-block;padding:4px 12px;background:#58a6ff26;color:var(--accent);border-radius:20px;font-size:.85rem;margin-bottom:20px}.hero-title{font-size:clamp(2rem,5vw,3rem);font-weight:800;line-height:1.2;margin:0 0 16px}.text-accent{color:var(--accent-green)}.hero-text{color:var(--text-muted);font-size:1.1rem;max-width:560px;margin:0 auto 32px}.hero-actions{display:flex;gap:12px;justify-content:center;flex-wrap:wrap}.features{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:20px;margin-bottom:48px}.feature-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:24px}.feature-icon{font-size:2rem;margin-bottom:12px}.feature-card h3{margin:0 0 8px;font-size:1.1rem}.feature-card p{margin:0;color:var(--text-muted);font-size:.9rem}.topics{text-align:center}.topics h2{margin-bottom:16px}.topic-tags{display:flex;flex-wrap:wrap;gap:8px;justify-content:center}.topic-tag{padding:6px 14px;background:var(--bg-card);border:1px solid var(--border);border-radius:20px;font-size:.9rem;color:var(--text-muted)}.home-progress,.progress-page{margin-bottom:32px}.progress-bar-wrap{height:8px;background:var(--bg-elevated);border-radius:4px;overflow:hidden;margin:12px 0}.progress-bar-wrap--large{height:12px}.progress-bar{height:100%;background:linear-gradient(90deg,var(--accent),var(--accent-green));border-radius:4px;transition:width .4s ease}.progress-text{color:var(--text-muted);font-size:.9rem}.progress-stats{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin-bottom:24px}.stat-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:20px;text-align:center}.stat-card--accent{border-color:var(--accent-green)}.stat-value{display:block;font-size:2rem;font-weight:700;color:var(--accent-green)}.stat-label{color:var(--text-muted);font-size:.85rem}.recent-lessons h2{font-size:1.2rem;margin-bottom:12px}.recent-list{list-style:none;padding:0;margin:0}.recent-list li{border-bottom:1px solid var(--border)}.recent-list a{display:flex;justify-content:space-between;align-items:center;padding:12px 0;color:var(--text);text-decoration:none}.recent-list a:hover{color:var(--accent)}.recent-category{color:var(--text-muted);font-size:.85rem}.empty-state{text-align:center;padding:48px 24px;color:var(--text-muted)}.page-header{margin-bottom:32px}.page-header h1{margin:0 0 8px;font-size:1.75rem}.page-header p{margin:0;color:var(--text-muted)}.filters{display:flex;gap:12px;margin-bottom:24px;flex-wrap:wrap}.filter-select{padding:8px 12px;background:var(--bg-card);border:1px solid var(--border);border-radius:8px;color:var(--text);font-size:.95rem;font-family:inherit}.lessons-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:16px}.lesson-card{display:block;background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:20px;color:var(--text);text-decoration:none;transition:border-color .15s,transform .15s}.lesson-card:hover{border-color:var(--accent);transform:translateY(-2px);text-decoration:none}.lesson-card--done{border-color:#3fb95066}.lesson-card-top{display:flex;justify-content:space-between;align-items:center;margin-bottom:8px}.lesson-category{font-size:.8rem;color:var(--accent);font-weight:500}.lesson-done-badge{font-size:.75rem;color:var(--accent-green)}.lesson-card-title{margin:0 0 8px;font-size:1.05rem}.lesson-card-desc{margin:0 0 12px;color:var(--text-muted);font-size:.9rem;line-height:1.5}.lesson-card-meta{display:flex;justify-content:space-between;align-items:center}.level-badge{font-size:.75rem;padding:2px 8px;border-radius:4px;font-weight:500}.level-beginner{background:#3fb95026;color:var(--accent-green)}.level-intermediate{background:#58a6ff26;color:var(--accent)}.level-advanced{background:#bc8cff26;color:var(--accent-purple)}.lesson-duration{font-size:.8rem;color:var(--text-muted)}.lesson-page{max-width:720px}.back-link{display:inline-block;margin-bottom:16px;color:var(--text-muted);font-size:.9rem}.lesson-header{margin-bottom:32px}.lesson-header h1{margin:8px 0;font-size:1.75rem}.lesson-meta-row{display:flex;gap:12px;align-items:center;flex-wrap:wrap}.lesson-intro{color:var(--text-muted);margin:0}.lesson-footer{margin-top:48px;padding-top:32px;border-top:1px solid var(--border)}.completed-banner{background:#3fb95026;color:var(--accent-green);padding:12px 16px;border-radius:8px;text-align:center;margin-bottom:24px}.auth-prompt{text-align:center;color:var(--text-muted);margin-bottom:24px}.lesson-nav{display:flex;justify-content:space-between;gap:16px}.lesson-nav-link{font-size:.9rem}.lesson-nav-next{margin-left:auto}.markdown h2{font-size:1.35rem;margin:32px 0 12px;padding-bottom:8px;border-bottom:1px solid var(--border)}.markdown h3{font-size:1.1rem;margin:24px 0 8px}.markdown p{margin:0 0 16px;color:var(--text-muted)}.markdown ul,.markdown ol{margin:0 0 16px;padding-left:24px;color:var(--text-muted)}.markdown li{margin-bottom:6px}.markdown blockquote{margin:0 0 16px;padding:12px 16px;border-left:3px solid var(--accent);background:var(--bg-card);color:var(--text-muted);border-radius:0 8px 8px 0}.inline-code{font-family:var(--font-mono);font-size:.88em;background:var(--bg-elevated);padding:2px 6px;border-radius:4px;color:var(--accent-green)}.code-block{position:relative;background:#0d1117;border:1px solid var(--border);border-radius:8px;padding:16px;margin:0 0 20px;overflow-x:auto}.code-block code{font-family:var(--font-mono);font-size:.88rem;line-height:1.6;color:#c9d1d9;white-space:pre}.code-lang{position:absolute;top:8px;right:12px;font-size:.75rem;color:var(--text-muted);text-transform:uppercase}.md-table{width:100%;border-collapse:collapse;margin:0 0 20px;font-size:.9rem}.md-table th,.md-table td{border:1px solid var(--border);padding:8px 12px;text-align:left}.md-table th{background:var(--bg-card);color:var(--text)}.md-table td{color:var(--text-muted)}.auth-page{display:flex;justify-content:center;align-items:flex-start;padding-top:32px}.auth-card{width:100%;max-width:400px;background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:32px}.auth-card h1{margin:0 0 8px;font-size:1.5rem}.auth-subtitle{color:var(--text-muted);margin:0 0 24px;font-size:.95rem}.auth-error{background:#f8514926;color:var(--danger);padding:10px 14px;border-radius:8px;margin-bottom:16px;font-size:.9rem}.auth-form label{display:block;margin-bottom:16px;font-size:.9rem;color:var(--text-muted)}.auth-form input{display:block;width:100%;margin-top:6px;padding:10px 12px;background:var(--bg);border:1px solid var(--border);border-radius:8px;color:var(--text);font-size:1rem;font-family:inherit}.auth-form input:focus{outline:none;border-color:var(--accent)}.auth-divider{text-align:center;margin:24px 0;position:relative}.auth-divider:before{content:"";position:absolute;left:0;right:0;top:50%;height:1px;background:var(--border)}.auth-divider span{position:relative;background:var(--bg-card);padding:0 12px;color:var(--text-muted);font-size:.85rem}.bot-auth{display:flex;flex-direction:column;gap:8px}.bot-form{padding:12px;background:var(--bg);border-radius:8px;margin-bottom:8px}.bot-hint{font-size:.85rem;color:var(--text-muted);margin:0 0 10px}.bot-form input{width:100%;padding:10px 12px;background:var(--bg-card);border:1px solid var(--border);border-radius:8px;color:var(--text);font-size:1.1rem;font-family:var(--font-mono);letter-spacing:4px;text-align:center;margin-bottom:8px}.auth-footer{text-align:center;margin-top:24px;color:var(--text-muted);font-size:.9rem}.loading-text,.error-text{text-align:center;padding:32px;color:var(--text-muted)}.error-text{color:var(--danger)}@media (max-width: 640px){.header{padding:0 12px;gap:8px}.nav{display:none}.main{padding:24px 16px 48px}.progress-stats{grid-template-columns:1fr}.hero{padding:32px 0 48px}}