:root {
    --primary: #0071e3;
    --primary-hover: #0077ed;
    --success: #34c759;
    --warning: #ff9500;
    --error: #ff3b30;
    --text: #1d1d1f;
    --text-secondary: #86868b;
    --background: #ffffff;
    --background-secondary: #f5f5f7;
    --border: #d2d2d7;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background: var(--background-secondary);
    color: var(--text);
    line-height: 1.5;
}

/* Layout */
.app-layout {
    display: flex;
    min-height: 100vh;
}

/* Sidebar */
.sidebar {
    width: 260px;
    background: var(--background);
    border-right: 1px solid var(--border);
    position: fixed;
    height: 100vh;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.sidebar-header {
    padding: 20px 24px;
    border-bottom: 1px solid var(--border);
}

.sidebar-header .logo {
    font-size: 18px;
    font-weight: 600;
    color: var(--text);
    text-decoration: none;
}

.sidebar-header .logo-subtitle {
    font-size: 12px;
    color: var(--text-secondary);
    display: block;
    margin-top: 2px;
}

.sidebar-nav {
    flex: 1;
    overflow-y: auto;
    padding: 16px 0;
}

.sidebar-nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.sidebar-nav li {
    list-style: none;
}

.sidebar-nav a {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 10px 24px;
    color: var(--text);
    text-decoration: none;
    font-size: 14px;
    transition: background 0.2s;
}

.sidebar-nav a:hover {
    background: var(--background-secondary);
}

.sidebar-nav a.active {
    background: var(--background-secondary);
    color: var(--primary);
    font-weight: 500;
}

.sidebar-nav svg {
    flex-shrink: 0;
    opacity: 0.7;
}

.sidebar-nav a.active svg {
    opacity: 1;
    stroke: var(--primary);
}

.nav-section {
    margin-top: 8px;
    padding-top: 16px;
    border-top: 1px solid var(--border);
}

.nav-section-title {
    display: block;
    padding: 8px 24px;
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-secondary);
}

.sidebar-footer {
    padding: 16px 24px;
    border-top: 1px solid var(--border);
    background: var(--background);
}

.user-info {
    margin-bottom: 12px;
}

.user-name {
    display: block;
    font-weight: 500;
    font-size: 14px;
    color: var(--text);
}

.user-role {
    display: block;
    font-size: 12px;
    color: var(--text-secondary);
}

.logout-btn {
    display: block;
    width: 100%;
    padding: 8px 12px;
    background: var(--background-secondary);
    border: 1px solid var(--border);
    border-radius: 6px;
    color: var(--text);
    text-decoration: none;
    text-align: center;
    font-size: 13px;
    transition: background 0.2s;
}

.logout-btn:hover {
    background: var(--border);
}

/* Main content */
.main-content {
    flex: 1;
    margin-left: 260px;
    padding: 32px;
    min-height: 100vh;
}

.page-header {
    margin-bottom: 32px;
}

.page-header h1 {
    font-size: 28px;
    font-weight: 600;
    margin-bottom: 4px;
}

.page-header p {
    color: var(--text-secondary);
}

/* Cards */
.card {
    background: var(--background);
    border-radius: 12px;
    padding: 24px;
    margin-bottom: 24px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border);
}

.card-header h2 {
    margin: 0;
    font-size: 18px;
}

/* Forms */
.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 6px;
    font-weight: 500;
    font-size: 14px;
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 15px;
    font-family: inherit;
    transition: border-color 0.2s;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary);
}

.form-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 16px;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 10px 20px;
    border: none;
    border-radius: 8px;
    font-size: 15px;
    font-weight: 500;
    cursor: pointer;
    text-decoration: none;
    transition: all 0.2s;
}

.btn-primary {
    background: var(--primary);
    color: white;
}

.btn-primary:hover {
    background: var(--primary-hover);
}

.btn-secondary {
    background: var(--background-secondary);
    color: var(--text);
    border: 1px solid var(--border);
}

.btn-secondary:hover {
    background: var(--border);
}

.btn-success {
    background: var(--success);
    color: white;
}

.btn-success:hover {
    background: #2db350;
}

.btn-danger {
    background: var(--error);
    color: white;
}

.btn-danger:hover {
    background: #e5342b;
}

.btn-sm {
    padding: 6px 12px;
    font-size: 13px;
}

/* Tables */
.table-container {
    overflow-x: auto;
}

table {
    width: 100%;
    border-collapse: collapse;
}

th, td {
    padding: 12px 16px;
    text-align: left;
    border-bottom: 1px solid var(--border);
}

th {
    font-weight: 600;
    font-size: 13px;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

tr:hover {
    background: var(--background-secondary);
}



/* Progress bar */
.progress-bar {
    height: 8px;
    background: var(--background-secondary);
    border-radius: 4px;
    overflow: hidden;
}

.progress-bar-fill {
    height: 100%;
    background: var(--success);
    border-radius: 4px;
    transition: width 0.3s;
}

/* Badges */
.badge {
    display: inline-block;
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 500;
}

.badge-info {
    background: #007aff20;
    color: #007aff;
}

.badge-success {
    background: #34c75920;
    color: #34c759;
}

.badge-warning {
    background: #ff950020;
    color: #ff9500;
}

.badge-danger {
    background: #ff3b3020;
    color: #ff3b30;
}

/* Alerts */
.alert {
    padding: 16px 20px;
    border-radius: 8px;
    margin-bottom: 24px;
}

.alert-success {
    background: #dcfce7;
    color: #166534;
    border: 1px solid #86efac;
}

.alert-warning {
    background: #fef3c7;
    color: #92400e;
    border: 1px solid #fcd34d;
}

.alert-error {
    background: #fee2e2;
    color: #991b1b;
    border: 1px solid #fca5a5;
}

/* Quiz styles */
.quiz-question {
    background: var(--background);
    border-radius: 12px;
    padding: 24px;
    margin-bottom: 20px;
}

.quiz-question h3 {
    margin-bottom: 16px;
    font-size: 16px;
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.quiz-option {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 14px 16px;
    background: var(--background-secondary);
    border: 2px solid transparent;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
}

.quiz-option:hover {
    border-color: var(--border);
}

.quiz-option.selected {
    border-color: var(--primary);
    background: #007aff10;
}

.quiz-option input.hidden-input {
    /* display: none; - REMOVED - was hiding checkboxes */
}

/* Course cards */
.course-card {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 16px;
    padding: 24px;
    color: white;
    margin-bottom: 24px;
}

.course-card h3 {
    font-size: 24px;
    margin-bottom: 8px;
}

.course-card p {
    opacity: 0.9;
    margin-bottom: 20px;
}

/* Lesson container */
.lesson-container {
    max-width: 900px;
    margin: 0 auto;
}

/* Video container */
.video-container {
    position: relative;
    padding-bottom: 56.25%;
    height: 0;
    overflow: hidden;
    max-width: 100%;
    margin: 20px 0;
    border-radius: 12px;
    background: #000;
}

.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

/* Auth pages */
.auth-container {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: 20px;
}

.auth-card {
    background: var(--background);
    padding: 40px;
    border-radius: 16px;
    width: 100%;
    max-width: 400px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
}

.auth-card h1 {
    text-align: center;
    margin-bottom: 8px;
}

.auth-card p {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 32px;
}

/* Responsive */
@media (max-width: 768px) {
    .sidebar {
        transform: translateX(-100%);
        z-index: 1000;
    }
    
    .sidebar.open {
        transform: translateX(0);
    }
    
    .main-content {
        margin-left: 0;
        padding: 20px;
    }
}