:root {
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --secondary-gradient: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --accent-gradient: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --success-gradient: linear-gradient(135deg, #43e97b 0%, #38f9d7 100%);

    --bg-primary: #0f0f23;
    --bg-secondary: #1a1a2e;
    --bg-tertiary: #252541;
    --bg-card: rgba(255, 255, 255, 0.05);

    --text-primary: #ffffff;
    --text-secondary: #a0a0c0;
    --text-muted: #6b6b8a;

    --border-color: rgba(255, 255, 255, 0.1);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);

    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;

    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
}

body::before {
    content: '';
    position: fixed;
    top: -50%;
    right: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(102, 126, 234, 0.1) 0%, transparent 50%);
    animation: rotate 30s linear infinite;
    pointer-events: none;
    z-index: 0;
}

@keyframes rotate {
    from {
        transform: rotate(0deg);
    }

    to {
        transform: rotate(360deg);
    }
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem;
    position: relative;
    z-index: 1;
}

/* Header Styles */
.header {
    background: var(--bg-card);
    backdrop-filter: blur(20px);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-lg);
    transition: transform var(--transition-normal);
}

.header:hover {
    transform: translateY(-2px);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1.5rem;
}

.logo-section {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.logo-icon {
    animation: float 3s ease-in-out infinite;
}

@keyframes float {

    0%,
    100% {
        transform: translateY(0);
    }

    50% {
        transform: translateY(-10px);
    }
}

.logo-text {
    font-size: 2rem;
    font-weight: 700;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.header-stats {
    display: flex;
    gap: 1rem;
}

.stat-badge {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.25rem;
    padding: 0.75rem 1.5rem;
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
}

.stat-badge:hover {
    transform: scale(1.05);
    border-color: rgba(102, 126, 234, 0.5);
}

.stat-label {
    font-size: 0.75rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-weight: 600;
}

.stat-value {
    font-size: 1.25rem;
    font-weight: 700;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Main Content */
.main-content {
    animation: fadeInUp 0.6s ease;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.course-header {
    margin-bottom: 2rem;
}

.course-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, #ffffff 0%, #a0a0c0 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.course-meta {
    display: flex;
    gap: 2rem;
    flex-wrap: wrap;
}

.meta-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.95rem;
    font-weight: 500;
    transition: color var(--transition-fast);
}

.meta-item:hover {
    color: var(--text-primary);
}

.meta-item svg {
    opacity: 0.7;
}

/* Sections Container */
.sections-container {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.section-card {
    background: var(--bg-card);
    backdrop-filter: blur(20px);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
    animation: slideIn 0.4s ease;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }

    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.section-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: rgba(102, 126, 234, 0.3);
}

.section-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.section-number {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--primary-gradient);
    border-radius: var(--radius-md);
    font-size: 1.25rem;
    font-weight: 700;
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.3);
}

.section-title {
    font-size: 1.5rem;
    font-weight: 600;
    flex: 1;
}

.section-badge {
    padding: 0.375rem 0.875rem;
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.section-summary {
    margin: 1rem 0;
    padding: 1rem;
    background: rgba(255, 255, 255, 0.02);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
}

.section-summary p {
    margin-bottom: 0.75rem;
}

.section-summary img {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-sm);
    margin: 0.75rem 0;
    box-shadow: var(--shadow-md);
}

.modules-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1rem;
}

.module-card {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 1.25rem;
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.module-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: var(--accent-gradient);
    transform: scaleY(0);
    transition: transform var(--transition-normal);
}

.module-card:hover::before {
    transform: scaleY(1);
}

.module-card:hover {
    transform: translateX(4px);
    border-color: rgba(79, 172, 254, 0.5);
    box-shadow: var(--shadow-md);
}

.module-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
}

.module-icon {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--accent-gradient);
    border-radius: var(--radius-sm);
    font-size: 1.125rem;
    flex-shrink: 0;
}

.module-info {
    flex: 1;
    min-width: 0;
}

.module-name {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.module-type {
    padding: 0.25rem 0.625rem;
    background: rgba(79, 172, 254, 0.2);
    border-radius: var(--radius-sm);
    font-size: 0.7rem;
    color: #4facfe;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    display: inline-block;
}

.module-intro {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 0.75rem;
    line-height: 1.6;
}

.module-intro p {
    margin-bottom: 0.5rem;
}

.module-intro img {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-sm);
    margin: 0.5rem 0;
}

.module-content {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 1rem;
    line-height: 1.5;
}

.module-content p {
    margin-bottom: 0.5rem;
}

.module-content img {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-sm);
    margin: 0.5rem 0;
}

.files-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.file-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem;
    background: var(--bg-secondary);
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-color);
    transition: all var(--transition-fast);
    text-decoration: none;
    color: var(--text-primary);
}

.file-item:hover {
    background: var(--bg-card);
    border-color: rgba(67, 233, 123, 0.5);
    transform: translateX(4px);
}

.file-icon {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--success-gradient);
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    flex-shrink: 0;
}

.file-info {
    flex: 1;
    min-width: 0;
}

.file-name {
    font-weight: 500;
    font-size: 0.95rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.file-meta {
    display: flex;
    gap: 1rem;
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 0.25rem;
}

.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-muted);
}

.empty-state-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

.empty-state-text {
    font-size: 1.125rem;
}

/* Loading Animation */
.loading {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 4rem;
}

.loading-spinner {
    width: 48px;
    height: 48px;
    border: 4px solid var(--bg-tertiary);
    border-top-color: #667eea;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }

    .header {
        padding: 1.5rem;
    }

    .header-content {
        flex-direction: column;
        align-items: flex-start;
    }

    .course-title {
        font-size: 2rem;
    }

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

    .course-meta {
        gap: 1rem;
    }
}

/* Scrollbar Styling */
::-webkit-scrollbar {
    width: 10px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--bg-tertiary);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--border-color);
}