/**
 * Unified AI Course Index Stylesheet
 * Used by all index.html files in the AI folder
 *
 * Theme colors can be customized per page using CSS variables:
 * --theme-primary: Primary color for headers, borders, accents
 * --theme-secondary: Secondary/gradient end color
 * --theme-accent: Accent color for highlighted text
 * --theme-gradient: Full gradient for header background
 */

/* Default theme (can be overridden per page) */
:root {
    --theme-primary: #1a1a2e;
    --theme-secondary: #0f3460;
    --theme-accent: #63b3ed;
    --theme-gradient: linear-gradient(135deg, #1a1a2e 0%, #16213e 50%, #0f3460 100%);
    --theme-overlay: radial-gradient(circle at 20% 50%, rgba(229, 62, 62, 0.1) 0%, transparent 50%),
                     radial-gradient(circle at 80% 50%, rgba(49, 130, 206, 0.1) 0%, transparent 50%);
}

/* Page Layout */
.course-page {
    min-height: 100vh;
    padding: 2rem 5%;
}

/* Breadcrumb */
.breadcrumb {
    padding: 1rem 0;
    font-size: 0.95rem;
    color: #666;
}

.breadcrumb a {
    color: var(--theme-primary);
    text-decoration: none;
}

.breadcrumb a:hover {
    text-decoration: underline;
}

/* Course Header */
.course-header {
    text-align: center;
    margin: 2rem 0 4rem 0;
    background: var(--theme-gradient);
    padding: 4rem 2rem;
    border-radius: 20px;
    box-shadow: 0 10px 40px rgba(26, 26, 46, 0.3);
    position: relative;
    overflow: hidden;
}

.course-header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--theme-overlay);
    opacity: 0.8;
}

.course-header h1 {
    font-size: 2.8rem;
    font-weight: 800;
    color: white;
    margin-bottom: 1rem;
    position: relative;
}

.course-header h1 strong {
    color: var(--theme-accent);
}

.course-header p {
    font-size: 1.25rem;
    color: #ffffff !important;
    max-width: 800px;
    margin: 0 auto;
    position: relative;
    line-height: 1.6;
}

/* Meta Badges */
.course-meta {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-top: 2rem;
    position: relative;
}

.meta-badge {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 25px;
    color: white;
    font-size: 0.9rem;
    backdrop-filter: blur(10px);
}

.meta-badge svg {
    width: 18px;
    height: 18px;
}

/* Course Container */
.course-container {
    max-width: 1200px;
    margin: 0 auto;
}

/* Course Overview Box */
.course-overview {
    background: linear-gradient(135deg, #f7fafc 0%, #edf2f7 100%);
    border-radius: 16px;
    padding: 2.5rem;
    margin-bottom: 3rem;
}

.course-overview h2 {
    font-size: 1.5rem;
    font-weight: 700;
    color: #2c3e50;
    margin-bottom: 1.5rem;
}

.overview-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
}

.overview-item {
    text-align: center;
    padding: 1.5rem;
    background: white;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

.overview-item h3 {
    font-size: 2rem;
    font-weight: 800;
    color: var(--theme-primary);
    margin-bottom: 0.5rem;
}

.overview-item p {
    font-size: 0.9rem;
    color: #666;
}

/* Session Sections */
.session-section {
    margin-bottom: 4rem;
}

.section-header {
    margin-bottom: 2rem;
    border-left: 4px solid var(--theme-primary);
    padding-left: 1.5rem;
}

.section-header h2 {
    font-size: 1.8rem;
    font-weight: 700;
    color: #2c3e50;
    margin-bottom: 0.5rem;
}

.section-header p {
    color: #666;
    font-size: 1rem;
}

/* Sessions Grid */
.sessions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 1.5rem;
}

/* Session Cards */
.session-card {
    background: white;
    border-radius: 12px;
    padding: 1.75rem;
    box-shadow: 0 2px 12px rgba(0,0,0,0.08);
    transition: all 0.3s ease;
    text-decoration: none;
    display: block;
    border: 2px solid transparent;
    position: relative;
}

.session-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.15);
    border-color: var(--theme-primary);
}

.session-number {
    display: inline-block;
    padding: 0.3rem 0.8rem;
    background: linear-gradient(135deg, var(--theme-primary) 0%, var(--theme-secondary) 100%);
    color: white;
    border-radius: 15px;
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.session-number.practical {
    background: linear-gradient(135deg, #e53e3e 0%, #c53030 100%);
}

.session-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: #2c3e50;
    margin-bottom: 0.75rem;
}

.session-card p {
    font-size: 0.95rem;
    color: #666;
    line-height: 1.5;
    margin-bottom: 1rem;
}

/* Topic Tags */
.session-topics {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.topic-tag {
    font-size: 0.75rem;
    padding: 0.25rem 0.6rem;
    background: #f0f4f8;
    color: #4a5568;
    border-radius: 10px;
}

/* Courses Grid (for main AI index) */
.courses-grid {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.course-card {
    background: white;
    border-radius: 16px;
    padding: 2rem;
    box-shadow: 0 4px 20px rgba(0,0,0,0.08);
    transition: all 0.3s ease;
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 1.5rem;
    border-left: 5px solid var(--card-color, var(--theme-primary));
    position: relative;
    overflow: hidden;
}

.course-card:hover {
    transform: translateX(8px);
    box-shadow: 0 8px 30px rgba(0,0,0,0.12);
}

.course-icon {
    width: 60px;
    height: 60px;
    min-width: 60px;
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--card-color, var(--theme-primary)) 0%, var(--card-secondary, var(--theme-secondary)) 100%);
}

.course-icon svg {
    width: 28px;
    height: 28px;
    color: white;
}

.course-content {
    flex: 1;
}

.course-content h3 {
    font-size: 1.35rem;
    font-weight: 700;
    color: #2c3e50;
    margin-bottom: 0.5rem;
}

.course-content > p {
    font-size: 0.95rem;
    color: #666;
    line-height: 1.5;
    margin-bottom: 0.75rem;
}

.course-content .course-meta {
    justify-content: flex-start;
    margin-top: 0;
    margin-bottom: 0.75rem;
}

.course-content .meta-item {
    font-size: 0.8rem;
    color: #888;
    font-weight: 500;
}

.course-topics {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.course-topics .topic {
    font-size: 0.75rem;
    padding: 0.25rem 0.6rem;
    background: #f0f0f0;
    color: #555;
    border-radius: 10px;
    font-weight: 500;
}

.course-arrow {
    width: 40px;
    height: 40px;
    min-width: 40px;
    border-radius: 50%;
    background: #f5f5f5;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
}

.course-arrow svg {
    width: 20px;
    height: 20px;
    color: #999;
    transition: all 0.3s ease;
}

.course-card:hover .course-arrow {
    background: var(--theme-primary);
}

.course-card:hover .course-arrow svg {
    color: white;
    transform: translateX(3px);
}

/* Course card color variants */
.course-card.data-exploration {
    --card-color: #6366f1;
    --card-secondary: #8b5cf6;
}

.course-card.computer-vision {
    --card-color: #1a1a2e;
    --card-secondary: #0f3460;
}

.course-card.adv-cv {
    --card-color: #1a5276;
    --card-secondary: #2980b9;
}

.course-card.vibe-coding {
    --card-color: #7c3aed;
    --card-secondary: #ec4899;
}

/* Responsive */
@media (max-width: 768px) {
    .course-header {
        padding: 3rem 1.5rem;
        margin: 1rem 0 3rem 0;
    }

    .course-header h1 {
        font-size: 2rem;
    }

    .course-header p {
        font-size: 1.05rem;
    }

    .course-meta {
        flex-direction: column;
        align-items: center;
        gap: 1rem;
    }

    .sessions-grid {
        grid-template-columns: 1fr;
    }

    .section-header h2 {
        font-size: 1.5rem;
    }

    .overview-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .course-card {
        flex-direction: column;
        align-items: flex-start;
        padding: 1.5rem;
    }

    .course-icon {
        width: 50px;
        height: 50px;
        min-width: 50px;
    }

    .course-icon svg {
        width: 24px;
        height: 24px;
    }

    .course-arrow {
        display: none;
    }

    .course-content .course-meta {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
    }
}