:root{--bg-primary: #0f0f23;--bg-secondary: #1a1a2e;--bg-tertiary: #16213e;--bg-card: #1e2a47;--bg-code: #0d1117;--text-primary: #e4e4e7;--text-secondary: #a1a1aa;--text-muted: #71717a;--accent-primary: #6366f1;--accent-secondary: #818cf8;--accent-gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 50%, #ec4899 100%);--border-color: rgba(99, 102, 241, .2);--border-hover: rgba(99, 102, 241, .5);--success: #22c55e;--warning: #eab308;--error: #ef4444;--font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;--font-mono: "JetBrains Mono", "Fira Code", monospace;--sidebar-width: 280px;--navbar-height: 64px;--shadow-sm: 0 1px 2px rgba(0, 0, 0, .3);--shadow-md: 0 4px 6px rgba(0, 0, 0, .4);--shadow-lg: 0 10px 15px rgba(0, 0, 0, .5);--shadow-glow: 0 0 20px rgba(99, 102, 241, .3);--transition-fast: .15s ease;--transition-normal: .25s ease;--transition-slow: .35s ease;--radius-sm: 6px;--radius-md: 10px;--radius-lg: 16px;--radius-xl: 24px}*,*:before,*:after{box-sizing:border-box;margin:0;padding:0}html{scroll-behavior:smooth}body{font-family:var(--font-sans);font-size:16px;line-height:1.6;color:var(--text-primary);background:var(--bg-primary);min-height:100vh;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}a{color:var(--accent-secondary);text-decoration:none;transition:color var(--transition-fast)}a:hover{color:var(--accent-primary)}.app-container{display:flex;min-height:100vh}.main-content{flex:1;margin-left:var(--sidebar-width);padding:calc(var(--navbar-height) + 2rem) 2rem 2rem;max-width:calc(100% - var(--sidebar-width))}@media (max-width: 768px){.main-content{margin-left:0;max-width:100%;padding:calc(var(--navbar-height) + 1rem) 1rem 1rem}}.navbar{position:fixed;top:0;left:var(--sidebar-width);right:0;height:var(--navbar-height);background:#0f0f23d9;-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px);border-bottom:1px solid var(--border-color);display:flex;align-items:center;justify-content:space-between;padding:0 2rem;z-index:100}.navbar-brand{display:flex;align-items:center;gap:12px}.navbar-logo{width:40px;height:40px;background:var(--accent-gradient);border-radius:var(--radius-md);display:flex;align-items:center;justify-content:center;font-weight:700;font-size:1.2rem;color:#fff}.navbar-title{font-size:1.25rem;font-weight:600;background:var(--accent-gradient);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.navbar-menu-btn{display:none;background:none;border:none;color:var(--text-primary);font-size:1.5rem;cursor:pointer;padding:8px}@media (max-width: 768px){.navbar{left:0;padding:0 1rem}.navbar-menu-btn{display:block}}.sidebar{position:fixed;left:0;top:0;bottom:0;width:var(--sidebar-width);background:var(--bg-secondary);border-right:1px solid var(--border-color);overflow-y:auto;z-index:200;transition:transform var(--transition-normal)}.sidebar-header{padding:1.5rem;border-bottom:1px solid var(--border-color)}.sidebar-logo{display:flex;align-items:center;gap:12px}.sidebar-logo-icon{width:48px;height:48px;background:var(--accent-gradient);border-radius:var(--radius-md);display:flex;align-items:center;justify-content:center;font-weight:700;font-size:1.5rem;color:#fff;box-shadow:var(--shadow-glow)}.sidebar-logo-text{font-size:1.1rem;font-weight:600}.sidebar-logo-text span{display:block;font-size:.75rem;color:var(--text-muted);font-weight:400}.sidebar-nav{padding:1rem 0}.sidebar-section-title{padding:.75rem 1.5rem;font-size:.7rem;text-transform:uppercase;letter-spacing:1.5px;color:var(--text-muted);font-weight:600}.sidebar-link{display:flex;align-items:center;gap:12px;padding:.75rem 1.5rem;color:var(--text-secondary);transition:all var(--transition-fast);border-left:3px solid transparent;font-size:.9rem}.sidebar-link:hover{background:#6366f11a;color:var(--text-primary);border-left-color:var(--accent-secondary)}.sidebar-link.active{background:#6366f126;color:var(--accent-secondary);border-left-color:var(--accent-primary);font-weight:500}.sidebar-link-number{width:24px;height:24px;background:var(--bg-tertiary);border-radius:var(--radius-sm);display:flex;align-items:center;justify-content:center;font-size:.75rem;font-weight:600}.sidebar-link.active .sidebar-link-number{background:var(--accent-primary);color:#fff}@media (max-width: 768px){.sidebar{transform:translate(-100%)}.sidebar.open{transform:translate(0)}.sidebar-overlay{position:fixed;top:0;right:0;bottom:0;left:0;background:#00000080;z-index:150;opacity:0;visibility:hidden;transition:all var(--transition-normal)}.sidebar-overlay.open{opacity:1;visibility:visible}}.home-hero{text-align:center;padding:4rem 2rem;background:var(--bg-secondary);border-radius:var(--radius-xl);margin-bottom:3rem;position:relative;overflow:hidden}.home-hero:before{content:"";position:absolute;top:0;left:0;right:0;height:4px;background:var(--accent-gradient)}.home-hero:after{content:"";position:absolute;top:-50%;right:-20%;width:400px;height:400px;background:radial-gradient(circle,rgba(99,102,241,.1) 0%,transparent 70%);border-radius:50%}.home-hero-icon{width:80px;height:80px;background:var(--accent-gradient);border-radius:var(--radius-lg);display:inline-flex;align-items:center;justify-content:center;font-size:2.5rem;color:#fff;margin-bottom:1.5rem;box-shadow:var(--shadow-glow)}.home-hero h1{font-size:2.5rem;font-weight:700;margin-bottom:1rem;background:var(--accent-gradient);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.home-hero p{font-size:1.1rem;color:var(--text-secondary);max-width:600px;margin:0 auto}.home-features{display:grid;grid-template-columns:repeat(auto-fit,minmax(250px,1fr));gap:1.5rem;margin-bottom:3rem}.feature-card{background:var(--bg-secondary);border-radius:var(--radius-lg);padding:1.5rem;border:1px solid var(--border-color);transition:all var(--transition-normal)}.feature-card:hover{border-color:var(--border-hover);transform:translateY(-4px);box-shadow:var(--shadow-lg)}.feature-icon{width:48px;height:48px;background:#6366f11a;border-radius:var(--radius-md);display:flex;align-items:center;justify-content:center;font-size:1.5rem;margin-bottom:1rem}.feature-card h3{font-size:1.1rem;font-weight:600;margin-bottom:.5rem}.feature-card p{font-size:.9rem;color:var(--text-secondary)}.home-lessons-title{font-size:1.5rem;font-weight:600;margin-bottom:1.5rem;display:flex;align-items:center;gap:12px}.home-lessons-title:after{content:"";flex:1;height:1px;background:var(--border-color)}.lessons-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:1.25rem}.lesson-card{background:var(--bg-secondary);border-radius:var(--radius-lg);padding:1.25rem;border:1px solid var(--border-color);transition:all var(--transition-normal);cursor:pointer;text-decoration:none;display:block}.lesson-card:hover{border-color:var(--accent-primary);transform:translateY(-2px);box-shadow:var(--shadow-md),var(--shadow-glow)}.lesson-card-header{display:flex;align-items:flex-start;gap:14px;margin-bottom:.75rem}.lesson-number{width:36px;height:36px;background:var(--accent-gradient);border-radius:var(--radius-md);display:flex;align-items:center;justify-content:center;font-weight:700;font-size:1rem;color:#fff;flex-shrink:0}.lesson-card h3{font-size:1rem;font-weight:600;color:var(--text-primary);line-height:1.4}.lesson-card p{font-size:.85rem;color:var(--text-secondary);line-height:1.5}.lesson-detail{max-width:800px;margin:0 auto}.lesson-header{margin-bottom:2rem;padding-bottom:1.5rem;border-bottom:1px solid var(--border-color)}.lesson-breadcrumb{display:flex;align-items:center;gap:8px;font-size:.85rem;color:var(--text-muted);margin-bottom:1rem}.lesson-breadcrumb a{color:var(--text-secondary)}.lesson-breadcrumb a:hover{color:var(--accent-secondary)}.lesson-header h1{font-size:2rem;font-weight:700;margin-bottom:.5rem;background:var(--accent-gradient);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.lesson-header p{font-size:1.1rem;color:var(--text-secondary)}.lesson-content{color:var(--text-primary)}.lesson-content h1{font-size:1.75rem;font-weight:700;margin:2rem 0 1rem;color:var(--text-primary)}.lesson-content h2{font-size:1.4rem;font-weight:600;margin:1.75rem 0 .75rem;color:var(--text-primary);padding-bottom:.5rem;border-bottom:1px solid var(--border-color)}.lesson-content h3{font-size:1.15rem;font-weight:600;margin:1.25rem 0 .5rem;color:var(--accent-secondary)}.lesson-content p{margin-bottom:1rem;line-height:1.75}.lesson-content ul,.lesson-content ol{margin-bottom:1rem;padding-left:1.5rem}.lesson-content li{margin-bottom:.5rem;line-height:1.6}.lesson-content strong{color:var(--accent-secondary);font-weight:600}.lesson-content blockquote{border-left:4px solid var(--accent-primary);padding:1rem 1.5rem;margin:1.5rem 0;background:#6366f11a;border-radius:0 var(--radius-md) var(--radius-md) 0;font-style:italic;color:var(--text-secondary)}.lesson-content table{width:100%;border-collapse:collapse;margin:1.5rem 0;font-size:.9rem}.lesson-content th,.lesson-content td{padding:.75rem 1rem;border:1px solid var(--border-color);text-align:left}.lesson-content th{background:var(--bg-tertiary);font-weight:600;color:var(--accent-secondary)}.lesson-content tr:nth-child(2n){background:#1a1a2e80}.lesson-content pre{margin:1.5rem 0;border-radius:var(--radius-md);overflow:hidden;box-shadow:var(--shadow-md)}.lesson-content code{font-family:var(--font-mono);font-size:.9rem}.lesson-content p code,.lesson-content li code{background:#6366f126;padding:.15em .4em;border-radius:4px;color:var(--accent-secondary);font-size:.85em}.lesson-nav{display:flex;justify-content:space-between;gap:1rem;margin-top:3rem;padding-top:2rem;border-top:1px solid var(--border-color)}.lesson-nav-btn{display:flex;align-items:center;gap:8px;padding:1rem 1.5rem;background:var(--bg-secondary);border:1px solid var(--border-color);border-radius:var(--radius-md);color:var(--text-secondary);transition:all var(--transition-fast);text-decoration:none;flex:1;max-width:45%}.lesson-nav-btn:hover{border-color:var(--accent-primary);color:var(--accent-secondary);transform:translateY(-2px)}.lesson-nav-btn.prev{justify-content:flex-start}.lesson-nav-btn.next{justify-content:flex-end;margin-left:auto}.lesson-nav-label{font-size:.75rem;text-transform:uppercase;letter-spacing:1px;color:var(--text-muted)}.lesson-nav-title{font-weight:500}.loading{display:flex;flex-direction:column;align-items:center;justify-content:center;padding:4rem 2rem;color:var(--text-secondary)}.loading-spinner{width:40px;height:40px;border:3px solid var(--border-color);border-top-color:var(--accent-primary);border-radius:50%;animation:spin 1s linear infinite;margin-bottom:1rem}@keyframes spin{to{transform:rotate(360deg)}}.error-message{text-align:center;padding:4rem 2rem;color:var(--error)}::-webkit-scrollbar{width:8px;height:8px}::-webkit-scrollbar-track{background:var(--bg-primary)}::-webkit-scrollbar-thumb{background:var(--bg-tertiary);border-radius:4px}::-webkit-scrollbar-thumb:hover{background:var(--accent-primary)}@media (max-width: 768px){.home-hero{padding:2.5rem 1.5rem}.home-hero h1{font-size:1.75rem}.home-hero p{font-size:1rem}.lesson-header h1{font-size:1.5rem}.lesson-nav{flex-direction:column}.lesson-nav-btn{max-width:100%}}