:root{--bg-primary:#0d1117;--bg-secondary:#161b22;--bg-tertiary:#1c2128;--bg-hover:#21262d;--text-primary:#fff;--text-secondary:#8b949e;--text-muted:#6e7681;--border-color:#30363d;--border-hover:#484f58;--error:#f85149;--success:#3fb950;--radius:8px;--radius-sm:6px;--transition:.15s ease;--font-family:"Be Vietnam Pro", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif}*{box-sizing:border-box;margin:0;padding:0}html{scroll-behavior:smooth}body{background-color:var(--bg-primary);color:var(--text-primary);font-family:var(--font-family);-webkit-font-smoothing:antialiased;line-height:1.6}a{color:var(--text-primary);transition:opacity var(--transition);text-decoration:none}a:hover{opacity:.75}h1,h2,h3,h4{margin-bottom:12px;font-weight:700;line-height:1.3}h1{font-size:2rem}h2{margin-top:32px;font-size:1.5rem}h3{font-size:1.15rem}p{color:var(--text-secondary);margin-bottom:12px}ul{list-style:none}img{max-width:100%;display:block}input,textarea,select{background-color:var(--bg-secondary);border:1px solid var(--border-color);border-radius:var(--radius-sm);color:var(--text-primary);width:100%;transition:border-color var(--transition);padding:10px 12px;font-family:inherit;font-size:.95rem}input:focus,textarea:focus,select:focus{border-color:var(--text-secondary);outline:none}textarea{resize:vertical;min-height:80px}button{cursor:pointer;border-radius:var(--radius-sm);background-color:var(--text-primary);color:var(--bg-primary);transition:opacity var(--transition), transform var(--transition);border:none;padding:10px 18px;font-family:inherit;font-size:.95rem;font-weight:600}button:hover:not(:disabled){opacity:.85}button:active:not(:disabled){transform:scale(.98)}button:disabled{opacity:.4;cursor:not-allowed}button[type=button]:not(.btn-activate-small){color:var(--text-primary);border:1px solid var(--border-color);background-color:#0000}button[type=button]:not(.btn-activate-small):hover:not(:disabled){background-color:var(--bg-hover);opacity:1}code{background-color:var(--bg-tertiary);border-radius:4px;padding:2px 6px;font-size:.9em}.page-container{max-width:1100px;margin:0 auto;padding:40px 24px}.error-text{color:var(--error)}.success-text{color:var(--success)}.navbar{background-color:var(--bg-secondary);border-bottom:1px solid var(--border-color);z-index:50;justify-content:space-between;align-items:center;padding:16px 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var(--transition);display:block;overflow:hidden}.course-card:hover{border-color:var(--border-hover);opacity:1;transform:translateY(-2px)}.course-card__thumbnail{aspect-ratio:16/9;background-color:var(--bg-tertiary);justify-content:center;align-items:center;display:flex}.course-card__thumbnail img{object-fit:cover;width:100%;height:100%}.course-card__thumbnail-placeholder{opacity:.3;font-size:2.5rem}.course-card__content{padding:16px}.course-card__title{margin-bottom:6px;font-size:1.05rem}.course-card__description{-webkit-line-clamp:2;-webkit-box-orient:vertical;margin-bottom:10px;font-size:.88rem;display:-webkit-box;overflow:hidden}.course-card__price{color:var(--text-primary);font-weight:700}.my-courses__empty{background-color:var(--bg-secondary);border-radius:var(--radius);border:1px dashed var(--border-color);padding:32px}.course-detail__thumbnail{border-radius:var(--radius);aspect-ratio:21/9;object-fit:cover;margin-bottom:20px}.course-detail__price{color:var(--text-primary);margin-bottom:20px;font-size:1.3rem;font-weight:700}.course-detail__curriculum{margin-top:32px}.course-detail__chapter{background-color:var(--bg-secondary);border:1px solid var(--border-color);border-radius:var(--radius);margin-bottom:12px;padding:18px 20px}.course-detail__chapter h3{margin-bottom:10px}.course-detail__chapter li{padding:6px 0}.course-detail__lesson-locked{color:var(--text-muted);align-items:center;gap:6px;display:inline-flex}.lesson-page{align-items:flex-start;gap:24px;max-width:1300px;margin:0 auto;padding:24px;display:flex}.lesson-page__content{flex:1;min-width:0}.lesson-page__blocked{background-color:var(--bg-secondary);border:1px solid var(--border-color);border-radius:var(--radius);text-align:center;padding:32px}.lesson-page__blocked 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var(--border-color);margin-top:16px;padding-top:16px}.chapter-list__cta .btn-activate-small{text-align:center;display:block}.btn-activate-small{background-color:var(--text-primary);color:var(--bg-primary);border-radius:var(--radius-sm);margin:12px 0;padding:10px 20px;font-weight:700;display:inline-block}.btn-activate-small:hover{opacity:.85}.login-page,.activate-page{justify-content:center;align-items:center;min-height:60vh;display:flex}.login-box,.activate-box{background-color:var(--bg-secondary);border:1px solid var(--border-color);border-radius:var(--radius);text-align:center;width:100%;max-width:420px;padding:40px}.btn-google-login{width:100%;margin-top:12px;padding:12px}.activate-input{text-align:center;letter-spacing:.05em;margin-bottom:12px;font-size:1.1rem}.btn-activate{width:100%}.admin-layout{min-height:100vh;display:flex}.admin-layout__sidebar{background-color:var(--bg-secondary);border-right:1px solid var(--border-color);flex-shrink:0;width:220px;padding:24px 16px}.admin-layout__sidebar h2{margin-bottom:20px;font-size:1.1rem}.admin-layout__sidebar nav{flex-direction:column;gap:4px;display:flex}.admin-layout__sidebar nav a{border-radius:var(--radius-sm);color:var(--text-secondary);padding:10px 12px;font-size:.92rem;font-weight:500}.admin-layout__sidebar nav a:hover{background-color:var(--bg-hover);color:var(--text-primary);opacity:1}.admin-layout__content{flex:1;min-width:0;padding:32px 40px}.admin-dashboard__stats{grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:16px;max-width:600px;margin-top:20px;display:grid}.admin-dashboard__stat-card{background-color:var(--bg-secondary);border:1px solid var(--border-color);border-radius:var(--radius);text-align:center;padding:20px}.admin-dashboard__stat-number{margin-bottom:4px;font-size:2rem;font-weight:800}.admin-form{background-color:var(--bg-secondary);border:1px solid var(--border-color);border-radius:var(--radius);flex-direction:column;gap:14px;max-width:560px;margin-bottom:32px;padding:24px;display:flex}.admin-form label{color:var(--text-secondary);flex-direction:column;gap:6px;font-size:.88rem;font-weight:600;display:flex}.admin-form__checkbox{align-items:center;flex-direction:row!important;gap:8px!important}.admin-form__checkbox input{width:auto}.admin-video-row{grid-template-columns:1fr 2fr auto auto auto;align-items:center;gap:8px;margin-bottom:8px;display:grid}.admin-video-row button{padding:8px 10px}.admin-table{border-collapse:collapse;background-color:var(--bg-secondary);border:1px solid var(--border-color);border-radius:var(--radius);width:100%;overflow:hidden}.admin-table th,.admin-table td{text-align:left;border-bottom:1px solid var(--border-color);padding:12px 16px;font-size:.9rem}.admin-table th{color:var(--text-secondary);background-color:var(--bg-tertiary);font-weight:600}.admin-table tr:last-child td{border-bottom:none}.admin-table tr:hover td{background-color:var(--bg-hover)}.admin-student-card{background-color:var(--bg-secondary);border:1px solid var(--border-color);border-radius:var(--radius);margin-bottom:16px;padding:20px}.admin-student-card ul{margin:10px 0}.admin-student-card li{color:var(--text-secondary);padding:4px 0;font-size:.9rem}@media (width<=900px){.lesson-page{flex-direction:column}.chapter-list{width:100%}.admin-layout{flex-direction:column}.admin-layout__sidebar{border-right:none;border-bottom:1px solid var(--border-color);width:100%}.admin-layout__sidebar nav{flex-flow:wrap}.admin-video-row{grid-template-columns:1fr}}@media (width<=600px){.navbar{padding:12px 16px}.navbar__links{gap:16px}.navbar__link span:not(.navbar__link-icon){display:none}.page-container{padding:24px 16px}h1{font-size:1.5rem}}