:root{--bg-primary:#f8fafc;--bg-secondary:#fff;--bg-tertiary:#f1f5f9;--text-primary:#0f172a;--text-secondary:#475569;--text-tertiary:#94a3b8;--accent-color:#3b82f6;--accent-hover:#2563eb;--border-color:#e2e8f0;--shadow-sm:0 1px 2px 0 #0000000d;--shadow-md:0 4px 6px -1px #0000001a, 0 2px 4px -2px #0000001a;--shadow-lg:0 10px 15px -3px #0000001a, 0 4px 6px -4px #0000001a;--radius-md:.5rem;--radius-lg:1rem}[data-theme=dark]{--bg-primary:#020617;--bg-secondary:#0f172a;--bg-tertiary:#1e293b;--text-primary:#f8fafc;--text-secondary:#94a3b8;--text-tertiary:#64748b;--accent-color:#38bdf8;--accent-hover:#7dd3fc;--border-color:#1e293b;--shadow-sm:0 1px 2px 0 #0000004d;--shadow-md:0 4px 6px -1px #0000004d, 0 2px 4px -2px #0000004d;--shadow-lg:0 10px 15px -3px #0006, 0 4px 6px -4px #0006}*{box-sizing:border-box;margin:0;padding:0}body{background-color:var(--bg-primary);color:var(--text-primary);-webkit-font-smoothing:antialiased;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica,Arial,sans-serif;line-height:1.5;transition:background-color .3s,color .3s}a{color:var(--accent-color);text-decoration:none;transition:color .2s}a:hover{color:var(--accent-hover)}button{cursor:pointer;border:none;outline:none;font-family:inherit}.container{max-width:1200px;margin:0 auto;padding:0 1.5rem}.flex{display:flex}.flex-col{flex-direction:column}.items-center{align-items:center}.justify-between{justify-content:space-between}.justify-center{justify-content:center}.gap-4{gap:1rem}.gap-2{gap:.5rem}.text-center{text-align:center}.mb-4{margin-bottom:1rem}.text-muted{color:var(--text-secondary)}.btn-primary{background-color:var(--accent-color);color:#fff;border-radius:var(--radius-md);padding:.5rem 1rem;font-weight:500;transition:background-color .2s}.btn-primary:hover{background-color:var(--accent-hover)}.btn-secondary{background-color:var(--bg-tertiary);color:var(--text-primary);border-radius:var(--radius-md);border:1px solid var(--border-color);padding:.5rem 1rem;font-weight:500;transition:background-color .2s}.btn-secondary:hover{background-color:var(--border-color)}.card{background-color:var(--bg-secondary);border:1px solid var(--border-color);border-radius:var(--radius-lg);box-shadow:var(--shadow-sm);transition:transform .2s,box-shadow .2s;overflow:hidden}.card:hover{box-shadow:var(--shadow-md);transform:translateY(-2px)}.input-field{border-radius:var(--radius-md);border:1px solid var(--border-color);background-color:var(--bg-primary);width:100%;color:var(--text-primary);padding:.75rem 1rem;font-size:1rem;transition:border-color .2s}.input-field:focus{border-color:var(--accent-color);outline:none}.navbar{background-color:var(--bg-secondary);border-bottom:1px solid var(--border-color);z-index:100;padding:1rem 0;position:sticky;top:0}.nav-logo{color:var(--text-primary);font-size:1.25rem;font-weight:700}.nav-link{color:var(--text-secondary);font-weight:500}.nav-link:hover{color:var(--text-primary)}.theme-toggle{color:var(--text-secondary);background:0 0;border-radius:50%;justify-content:center;align-items:center;padding:.5rem;transition:background-color .2s,color .2s;display:flex}.theme-toggle:hover{background-color:var(--bg-tertiary);color:var(--text-primary)}.skeleton-card{flex-direction:column;padding:0;display:flex;overflow:hidden}.skeleton-img{border-radius:0;width:100%;height:200px}.skeleton-content{flex-direction:column;gap:1rem;padding:1.5rem;display:flex}.skeleton-title{border-radius:4px;width:80%;height:24px}.skeleton-text{border-radius:4px;width:100%;height:16px}.skeleton-text.short{width:60%}.skeleton-btn{border-radius:8px;width:100%;height:40px;margin-top:auto}.skeleton{background:linear-gradient(90deg, var(--bg-secondary) 25%, var(--bg-primary) 50%, var(--bg-secondary) 75%);background-size:200% 100%;animation:1.5s infinite loadingPulse}@keyframes loadingPulse{0%{background-position:200% 0}to{background-position:-200% 0}}.hero{text-align:center;padding:4rem 0 3rem}.hero-title{letter-spacing:-.025em;background:linear-gradient(to right, var(--accent-color), #8b5cf6);-webkit-text-fill-color:transparent;-webkit-background-clip:text;margin-bottom:1rem;font-size:3rem;font-weight:800}.hero-subtitle{color:var(--text-secondary);max-width:600px;margin:0 auto;font-size:1.25rem}.section-title{color:var(--text-primary);margin-bottom:2rem;font-size:1.5rem;font-weight:700}.course-grid{grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:2rem;display:grid}.course-actions{align-items:center;gap:.5rem;margin-top:auto;display:flex}.hero-section{background:linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);border-bottom:1px solid var(--border-color);margin-top:-2rem;padding:6rem 2rem;position:relative;overflow:hidden}.hero-section:before{content:"";background:radial-gradient(circle at center, var(--accent-color) 0%, transparent 70%);opacity:.05;pointer-events:none;position:absolute;inset:0}.hero-content{z-index:1;max-width:800px;margin:0 auto;position:relative}.hero-title{background:linear-gradient(to right, var(--text-primary), var(--accent-color));-webkit-text-fill-color:transparent;-webkit-background-clip:text;background-clip:text;margin-bottom:1.5rem;font-size:3.5rem;line-height:1.2}.hero-subtitle{color:var(--text-muted);margin-bottom:2.5rem;font-size:1.25rem}@media (width<=768px){.hero-title{font-size:2.5rem}}.course-card{flex-direction:column;height:100%;display:flex}.course-img{object-fit:cover;width:100%;height:200px}.course-content{flex:1;padding:1.5rem}.course-title{color:var(--text-primary);margin-bottom:.5rem;font-size:1.25rem;font-weight:600}.course-description{color:var(--text-secondary);margin-bottom:1.5rem;font-size:.95rem}.course-price{color:var(--text-primary);font-size:1.25rem;font-weight:700}.loading-state{text-align:center;color:var(--text-secondary);padding:3rem}.auth-container{min-height:calc(100vh - 200px)}.auth-card{width:100%;max-width:450px;padding:2.5rem}.auth-header{text-align:center;margin-bottom:2rem}.auth-icon{color:var(--accent-color);margin-bottom:1rem}.auth-header h2{color:var(--text-primary);margin-bottom:.5rem;font-size:1.75rem}.auth-subtitle{color:var(--text-secondary);font-size:.95rem}.input-group{flex-direction:column;gap:.5rem;width:100%;display:flex}.input-group label{color:var(--text-primary);font-size:.875rem;font-weight:500}.auth-submit{margin-top:1rem;padding:.75rem;font-size:1rem}.auth-footer{text-align:center;color:var(--text-secondary);margin-top:2rem;font-size:.95rem}.text-btn{color:var(--accent-color);cursor:pointer;background:0 0;border:none;font-weight:600}.text-btn:hover{text-decoration:underline}.dashboard-container{padding-top:3rem;padding-bottom:4rem}.modal-overlay{-webkit-backdrop-filter:blur(4px);backdrop-filter:blur(4px);z-index:1000;background-color:#0009;justify-content:center;align-items:center;padding:1rem;display:flex;position:fixed;inset:0}.modal-content{width:100%;max-width:500px;max-height:90vh;padding:2rem;overflow-y:auto}.my-courses-header{border-bottom:1px solid var(--border-color);margin-bottom:3rem;padding-bottom:1rem}.empty-state{text-align:center;flex-direction:column;grid-column:1/-1;align-items:center;gap:1rem;padding:4rem 2rem;display:flex}.empty-state h3{color:var(--text-primary);font-size:1.5rem}.empty-state p{color:var(--text-secondary);margin-bottom:1rem}.course-player-layout{height:calc(100vh - 73px);margin-top:-2rem;display:flex;overflow:hidden}.player-sidebar{background-color:var(--bg-secondary);border-right:1px solid var(--border-color);flex-direction:column;width:300px;display:flex;overflow-y:auto}.back-btn{color:var(--text-secondary);cursor:pointer;border:none;border-bottom:1px solid var(--border-color);background:0 0;padding:1rem;font-weight:500}.back-btn:hover{color:var(--text-primary);background-color:var(--bg-tertiary)}.sidebar-title{color:var(--text-primary);padding:1.5rem 1rem 1rem;font-size:1.1rem;font-weight:600}.no-lessons{color:var(--text-secondary);padding:0 1rem;font-size:.9rem}.lesson-list{margin:0;padding:0;list-style:none}.lesson-item{cursor:pointer;color:var(--text-secondary);border-left:3px solid #0000;padding:1rem;transition:all .2s}.lesson-item:hover{background-color:var(--bg-tertiary);color:var(--text-primary)}.lesson-item.active{background-color:var(--bg-tertiary);color:var(--accent-color);border-left-color:var(--accent-color)}.lesson-name{font-size:.95rem;font-weight:500}.player-main{background-color:var(--bg-primary);flex:1;padding:2rem;overflow-y:auto}.video-container{max-width:900px;margin:0 auto}.video-title{color:var(--text-primary);margin-bottom:1rem;font-size:1.5rem;font-weight:700}.video-wrapper{aspect-ratio:16/9;background-color:#000;width:100%;margin-bottom:2rem;padding:0;overflow:hidden}.embedded-video{width:100%;height:100%;display:block}.lesson-description{padding:1.5rem}.lesson-description h3{color:var(--text-primary);margin-bottom:.5rem;font-size:1.1rem}.lesson-description p{color:var(--text-secondary);line-height:1.6}