/* ============================================
   CSS Variables & Reset
   ============================================ */
:root {
    --color-primary: #0078d4;
    --color-primary-dark: #005a9e;
    --color-primary-light: #deecf9;
    --color-success: #107c10;
    --color-warning: #ffb900;
    --color-error: #d13438;
    
    --color-bg: #f5f5f5;
    --color-bg-card: #ffffff;
    --color-bg-sidebar: #fafafa;
    --color-bg-player: #1a1a2e;
    
    --color-text: #323130;
    --color-text-secondary: #605e5c;
    --color-text-light: #ffffff;
    --color-text-muted: #8a8886;
    
    --color-border: #e1dfdd;
    --color-border-light: #f3f2f1;
    
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-full: 9999px;
    
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
}

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
}

body {
    font-family: var(--font-sans);
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.5;
    min-height: 100vh;
}

/* ============================================
   Header
   ============================================ */
.header {
    background: var(--color-bg-card);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0.75rem 1.5rem;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo-icon {
    width: 28px;
    height: 28px;
    color: var(--color-primary);
}

.logo-text {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-text);
}

/* Mobile menu button - hidden on desktop */
.btn-mobile-menu {
    display: none;
    background: none;
    border: none;
    padding: 0.5rem;
    cursor: pointer;
    color: var(--color-text);
    border-radius: var(--radius-sm);
}

.btn-mobile-menu:hover {
    background: var(--color-border-light);
}

.btn-mobile-menu svg {
    width: 24px;
    height: 24px;
}

.certification-selector {
    display: flex;
    gap: 0.75rem;
}

.certification-selector select {
    padding: 0.5rem 1rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-bg-card);
    font-size: 0.875rem;
    color: var(--color-text);
    cursor: pointer;
    transition: border-color var(--transition-fast);
}

.certification-selector select:hover {
    border-color: var(--color-primary);
}

.certification-selector select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 2px var(--color-primary-light);
}

.btn-signin {
    padding: 0.5rem 1rem;
    background: var(--color-primary);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: background var(--transition-fast);
}

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

/* ============================================
   Main Layout
   ============================================ */
.main-content {
    display: grid;
    grid-template-columns: 320px 1fr;
    max-width: 1400px;
    margin: 0 auto;
    min-height: calc(100vh - 60px);
}

@media (max-width: 900px) {
    .main-content {
        grid-template-columns: 1fr;
    }
    
    /* Player section takes full width on mobile */
    .player-section {
        width: 100%;
        min-height: auto;
    }
    
    /* Show mobile menu button */
    .btn-mobile-menu {
        display: block;
    }
    
    /* Mobile sidebar as slide-out drawer */
    .sidebar {
        display: block;
        position: fixed;
        left: 0;
        top: 0;
        width: 320px;
        max-width: 85vw;
        height: 100vh;
        z-index: 1000;
        transform: translateX(-100%);
        transition: transform var(--transition-normal);
        box-shadow: var(--shadow-lg);
    }
    
    .sidebar.open {
        transform: translateX(0);
    }
    
    /* Overlay behind sidebar */
    .sidebar-overlay {
        display: none;
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background: rgba(0, 0, 0, 0.5);
        z-index: 999;
    }
    
    .sidebar-overlay.visible {
        display: block;
    }
}

/* ============================================
   Sidebar
   ============================================ */
.sidebar {
    background: var(--color-bg-sidebar);
    border-right: 1px solid var(--color-border);
    overflow-y: auto;
    height: calc(100vh - 60px);
    position: sticky;
    top: 60px;
}

.sidebar-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--color-border);
}

.sidebar-header h2 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

/* Course Stats */
.course-stats {
    background: var(--color-primary-light);
    border-radius: var(--radius-md);
    padding: 0.75rem 1rem;
    margin-bottom: 1rem;
}

.stat-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.25rem 0;
}

.stat-row:first-child {
    padding-top: 0;
}

.stat-row:last-child {
    padding-bottom: 0;
}

.stat-label {
    font-size: 0.8125rem;
    color: var(--color-text-secondary);
}

.stat-value {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-primary-dark);
}

.progress-summary {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.progress-text {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
}

.progress-bar {
    height: 6px;
    background: var(--color-border);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--color-success);
    border-radius: var(--radius-full);
    transition: width var(--transition-normal);
    width: 0%;
}

.episode-list {
    padding: 0.5rem;
}

/* ============================================
   Domain Sections (Collapsible)
   ============================================ */
.domain-section {
    margin-bottom: 0.5rem;
    border-radius: var(--radius-md);
    background: var(--color-bg-card);
    border: 1px solid var(--color-border-light);
    overflow: hidden;
}

.domain-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.75rem 1rem;
    cursor: pointer;
    background: var(--color-bg-sidebar);
    border-bottom: 1px solid var(--color-border-light);
    transition: background var(--transition-fast);
}

.domain-header:hover {
    background: var(--color-border-light);
}

.domain-header-left {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex: 1;
    min-width: 0;
}

.domain-chevron {
    width: 16px;
    height: 16px;
    color: var(--color-text-muted);
    transition: transform var(--transition-fast);
    flex-shrink: 0;
}

.domain-section.collapsed .domain-chevron {
    transform: rotate(-90deg);
}

.domain-header .domain-title {
    font-size: 0.8125rem;
    font-weight: 600;
    color: var(--color-text);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    text-transform: none;
    letter-spacing: normal;
    padding: 0;
    margin: 0;
}

.domain-meta {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    flex-shrink: 0;
    margin-left: 0.5rem;
}

.domain-progress {
    font-size: 0.6875rem;
    color: var(--color-text-muted);
    font-weight: 500;
}

.domain-duration {
    font-size: 0.6875rem;
    color: var(--color-primary);
    font-weight: 600;
    min-width: 35px;
    text-align: right;
}

.domain-progress-bar {
    width: 40px;
    height: 4px;
    background: var(--color-border);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.domain-progress-fill {
    height: 100%;
    background: var(--color-success);
    border-radius: var(--radius-full);
    transition: width var(--transition-normal);
}

.domain-episodes {
    padding: 0.25rem 0.5rem;
    max-height: 1000px;
    overflow: hidden;
    transition: max-height 0.3s ease, padding 0.3s ease;
}

.domain-section.collapsed .domain-episodes {
    max-height: 0;
    padding: 0 0.5rem;
}

.domain-section.collapsed .domain-header {
    border-bottom-color: transparent;
}

.domain-group {
    margin-bottom: 1.5rem;
}

.episode-item {
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
    padding: 0.75rem;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: background var(--transition-fast);
}

.episode-item:hover {
    background: var(--color-border-light);
}

.episode-item.active {
    background: var(--color-primary-light);
}

.episode-item.completed .episode-number {
    background: var(--color-success);
    color: white;
}

.episode-number {
    flex-shrink: 0;
    width: 28px;
    height: 28px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-border);
    color: var(--color-text-secondary);
    border-radius: var(--radius-full);
    font-size: 0.75rem;
    font-weight: 600;
}

.episode-details {
    flex: 1;
    min-width: 0;
}

.episode-item-title {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.episode-duration {
    font-size: 0.75rem;
    color: var(--color-text-muted);
    margin-top: 0.25rem;
}

.amendment-badge {
    display: inline-block;
    padding: 0.125rem 0.375rem;
    background: var(--color-warning);
    color: #1a1a1a;
    font-size: 0.625rem;
    font-weight: 600;
    border-radius: var(--radius-sm);
    text-transform: uppercase;
    margin-left: 0.5rem;
}

/* ============================================
   Player Section
   ============================================ */
.player-section {
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.now-playing {
    background: var(--color-bg-card);
    border-radius: var(--radius-lg);
    padding: 2rem;
    box-shadow: var(--shadow-md);
}

.episode-info {
    text-align: center;
    margin-bottom: 2rem;
}

.episode-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 0.5rem;
}

.episode-domain {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    margin-bottom: 1rem;
}

.episode-topics {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    justify-content: center;
}

.topic-tag {
    padding: 0.25rem 0.75rem;
    background: var(--color-primary-light);
    color: var(--color-primary-dark);
    font-size: 0.75rem;
    border-radius: var(--radius-full);
}

/* ============================================
   Audio Player
   ============================================ */
.audio-player {
    background: var(--color-bg-player);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
}

.player-controls {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.btn-control {
    background: none;
    border: none;
    color: var(--color-text-light);
    cursor: pointer;
    transition: transform var(--transition-fast), opacity var(--transition-fast);
    opacity: 0.8;
}

.btn-control:hover {
    opacity: 1;
    transform: scale(1.1);
}

.btn-control svg {
    width: 32px;
    height: 32px;
}

.btn-play {
    width: 64px;
    height: 64px;
    background: var(--color-primary);
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 1;
}

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

.btn-play svg {
    width: 28px;
    height: 28px;
}

.player-progress {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.time-current,
.time-total {
    font-size: 0.75rem;
    color: var(--color-text-light);
    opacity: 0.7;
    font-variant-numeric: tabular-nums;
    min-width: 40px;
}

.time-total {
    text-align: right;
}

.progress-track {
    flex: 1;
    height: 6px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-full);
    position: relative;
    cursor: pointer;
}

.progress-played {
    height: 100%;
    background: var(--color-primary);
    border-radius: var(--radius-full);
    position: absolute;
    top: 0;
    left: 0;
    width: 0%;
    transition: width 100ms linear;
}

.progress-handle {
    width: 14px;
    height: 14px;
    background: white;
    border-radius: var(--radius-full);
    position: absolute;
    top: 50%;
    transform: translate(-50%, -50%);
    left: 0%;
    box-shadow: var(--shadow-md);
    opacity: 0;
    transition: opacity var(--transition-fast);
}

.progress-track:hover .progress-handle {
    opacity: 1;
}

.player-extras {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.speed-control {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--color-text-light);
    opacity: 0.7;
    font-size: 0.75rem;
}

.speed-control select {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    color: white;
    padding: 0.25rem 0.5rem;
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    cursor: pointer;
}

.btn-transcript {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    color: var(--color-text-light);
    padding: 0.5rem 1rem;
    border-radius: var(--radius-md);
    font-size: 0.75rem;
    cursor: pointer;
    transition: background var(--transition-fast);
}

.btn-transcript:hover {
    background: rgba(255, 255, 255, 0.2);
}

.btn-transcript svg {
    width: 16px;
    height: 16px;
}

/* ============================================
   Complete Section
   ============================================ */
.complete-section {
    margin-top: 1.5rem;
    display: flex;
    justify-content: center;
}

.checkbox-complete {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    cursor: pointer;
    font-size: 0.875rem;
    color: var(--color-text-secondary);
}

.checkbox-complete input {
    display: none;
}

.checkmark {
    width: 22px;
    height: 22px;
    border: 2px solid var(--color-border);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.checkbox-complete input:checked + .checkmark {
    background: var(--color-success);
    border-color: var(--color-success);
}

.checkbox-complete input:checked + .checkmark::after {
    content: '✓';
    color: white;
    font-size: 0.875rem;
    font-weight: bold;
}

/* ============================================
   Transcript Panel
   ============================================ */
.transcript-panel {
    background: var(--color-bg-card);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    display: none;
}

.transcript-panel.visible {
    display: block;
}

.transcript-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--color-border);
}

.transcript-header h3 {
    font-size: 1rem;
    font-weight: 600;
}

.btn-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--color-text-muted);
    cursor: pointer;
    line-height: 1;
}

.btn-close:hover {
    color: var(--color-text);
}

.transcript-content {
    padding: 1.5rem;
    max-height: 400px;
    overflow-y: auto;
    font-size: 0.9375rem;
    line-height: 1.7;
    color: var(--color-text);
}

.transcript-content p {
    margin-bottom: 1rem;
}

/* ============================================
   Loading State
   ============================================ */
.loading {
    text-align: center;
    padding: 2rem;
    color: var(--color-text-muted);
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 600px) {
    .header-content {
        flex-wrap: wrap;
        gap: 1rem;
    }
    
    .certification-selector {
        order: 3;
        width: 100%;
    }
    
    .certification-selector select {
        flex: 1;
    }
    
    .player-section {
        padding: 1rem;
    }
    
    .now-playing {
        padding: 1.5rem;
    }
    
    .episode-title {
        font-size: 1.25rem;
    }
}