:root{--bg-primary:#0f0f1a;--bg-secondary:#1a1a2e;--bg-tertiary:#252539;--text-primary:#fff;--text-secondary:#9ca3af;--primary-color:#3b82f6;--accent-color:#10b981;--border-color:#ffffff1a}*{box-sizing:border-box;margin:0;padding:0}body{background-color:var(--bg-primary);color:var(--text-primary);-webkit-font-smoothing:antialiased;min-height:100vh;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif}#root{flex-direction:column;min-height:100vh;display:flex}.container{max-width:600px;margin:0 auto;padding:0 16px}.loading-screen{flex-direction:column;justify-content:center;align-items:center;gap:16px;min-height:100vh;display:flex}.loading-spinner{border:3px solid var(--border-color);border-top-color:var(--primary-color);border-radius:50%;width:40px;height:40px;animation:1s linear infinite spin}@keyframes spin{to{transform:rotate(360deg)}}.error-screen{text-align:center;flex-direction:column;justify-content:center;align-items:center;min-height:100vh;padding:24px;display:flex}.error-icon{margin-bottom:16px;font-size:48px}.error-message{color:var(--text-secondary);font-size:16px}.course-header{background:var(--bg-secondary);border-bottom:1px solid var(--border-color);padding:20px 16px}.course-logo{object-fit:cover;border-radius:12px;width:48px;height:48px;margin-bottom:12px}.course-brand{color:var(--text-secondary);margin-bottom:4px;font-size:14px}.course-title{margin-bottom:8px;font-size:24px;font-weight:700}.course-description{color:var(--text-secondary);font-size:14px;line-height:1.5}.course-progress{align-items:center;gap:12px;padding:16px;display:flex}.progress-bar{background:var(--bg-tertiary);border-radius:4px;flex:1;height:8px;overflow:hidden}.progress-fill{background:var(--primary-color);border-radius:4px;height:100%;transition:width .3s}.progress-text{color:var(--text-secondary);white-space:nowrap;font-size:14px}.modules-list{padding:16px}.module-card{background:var(--bg-secondary);border-radius:12px;margin-bottom:12px;overflow:hidden}.module-header{cursor:pointer;justify-content:space-between;align-items:center;padding:16px;display:flex}.module-title{font-size:16px;font-weight:600}.module-lessons-count{color:var(--text-secondary);font-size:14px}.lessons-list{border-top:1px solid var(--border-color)}.lesson-item{cursor:pointer;align-items:center;gap:12px;padding:12px 16px;transition:background .2s;display:flex}.lesson-item:hover{background:var(--bg-tertiary)}.lesson-status{border:2px solid var(--border-color);border-radius:50%;flex-shrink:0;justify-content:center;align-items:center;width:24px;height:24px;display:flex}.lesson-status.completed{background:var(--accent-color);border-color:var(--accent-color)}.lesson-status.completed:after{content:"✓";color:#fff;font-size:12px}.lesson-info{flex:1}.lesson-title{margin-bottom:2px;font-size:14px}.lesson-duration{color:var(--text-secondary);font-size:12px}.lesson-header{background:var(--bg-secondary);border-bottom:1px solid var(--border-color);align-items:center;gap:12px;padding:16px;display:flex}.back-button{color:var(--text-primary);cursor:pointer;background:0 0;border:none;padding:8px;font-size:20px}.lesson-header-title{font-size:18px;font-weight:600}.lesson-content{padding:20px 16px;line-height:1.8}.lesson-content img{border-radius:8px;max-width:100%;margin:16px 0}.lesson-content iframe{aspect-ratio:16/9;border:none;border-radius:8px;width:100%;margin:16px 0}.complete-button{background:var(--primary-color);color:#fff;cursor:pointer;border:none;border-radius:12px;padding:16px;font-size:16px;font-weight:600;transition:transform .2s,opacity .2s;position:fixed;bottom:24px;left:16px;right:16px}.complete-button:active{transform:scale(.98)}.complete-button.completed{background:var(--accent-color)}