:root{--bg-primary: #0f0f1a;--bg-secondary: #1a1a2e;--bg-tertiary: #252539;--text-primary: #ffffff;--text-secondary: #9ca3af;--primary-color: #3b82f6;--accent-color: #10b981;--border-color: rgba(255, 255, 255, .1)}*{margin:0;padding:0;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;background-color:var(--bg-primary);color:var(--text-primary);min-height:100vh;-webkit-font-smoothing:antialiased}#root{min-height:100vh;display:flex;flex-direction:column}.container{max-width:600px;margin:0 auto;padding:0 16px}.loading-screen{display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:100vh;gap:16px}.loading-spinner{width:40px;height:40px;border:3px solid var(--border-color);border-top-color:var(--primary-color);border-radius:50%;animation:spin 1s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}.error-screen{display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:100vh;padding:24px;text-align:center}.error-icon{font-size:48px;margin-bottom:16px}.error-message{color:var(--text-secondary);font-size:16px}.course-header{padding:20px 16px;background:var(--bg-secondary);border-bottom:1px solid var(--border-color)}.course-logo{width:48px;height:48px;border-radius:12px;margin-bottom:12px;object-fit:cover}.course-brand{font-size:14px;color:var(--text-secondary);margin-bottom:4px}.course-title{font-size:24px;font-weight:700;margin-bottom:8px}.course-description{font-size:14px;color:var(--text-secondary);line-height:1.5}.course-progress{padding:16px;display:flex;align-items:center;gap:12px}.progress-bar{flex:1;height:8px;background:var(--bg-tertiary);border-radius:4px;overflow:hidden}.progress-fill{height:100%;background:var(--primary-color);border-radius:4px;transition:width .3s ease}.progress-text{font-size:14px;color:var(--text-secondary);white-space:nowrap}.modules-list{padding:16px}.module-card{background:var(--bg-secondary);border-radius:12px;margin-bottom:12px;overflow:hidden}.module-header{padding:16px;display:flex;justify-content:space-between;align-items:center;cursor:pointer}.module-title{font-size:16px;font-weight:600}.module-lessons-count{font-size:14px;color:var(--text-secondary)}.lessons-list{border-top:1px solid var(--border-color)}.lesson-item{display:flex;align-items:center;padding:12px 16px;gap:12px;cursor:pointer;transition:background .2s}.lesson-item:hover{background:var(--bg-tertiary)}.lesson-status{width:24px;height:24px;border-radius:50%;border:2px solid var(--border-color);display:flex;align-items:center;justify-content:center;flex-shrink:0}.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{font-size:14px;margin-bottom:2px}.lesson-duration{font-size:12px;color:var(--text-secondary)}.lesson-header{padding:16px;background:var(--bg-secondary);border-bottom:1px solid var(--border-color);display:flex;align-items:center;gap:12px}.back-button{background:none;border:none;color:var(--text-primary);font-size:20px;cursor:pointer;padding:8px}.lesson-header-title{font-size:18px;font-weight:600}.lesson-content{padding:20px 16px;line-height:1.8}.lesson-content img{max-width:100%;border-radius:8px;margin:16px 0}.lesson-content iframe{width:100%;aspect-ratio:16/9;border-radius:8px;margin:16px 0;border:none}.complete-button{position:fixed;bottom:24px;left:16px;right:16px;padding:16px;background:var(--primary-color);color:#fff;border:none;border-radius:12px;font-size:16px;font-weight:600;cursor:pointer;transition:transform .2s,opacity .2s}.complete-button:active{transform:scale(.98)}.complete-button.completed{background:var(--accent-color)}