:root {
    /* Color Palette */
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #818cf8;
    --secondary: #ec4899;
    --success: #10b981;
    --error: #ef4444;
    --warning: #f59e0b;
    
    /* Neutrals */
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;
    
    /* Glass Effect */
    --glass-bg: rgba(30, 41, 59, 0.7);
    --glass-border: rgba(148, 163, 184, 0.1);
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.5rem;
    --radius-md: 1rem;
    --radius-lg: 1.5rem;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.3);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: linear-gradient(135deg, #0f172a 0%, #1e293b 50%, #0f172a 100%);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
    overflow-x: hidden;
}

/* Animated Background */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle at 20% 50%, rgba(99, 102, 241, 0.1) 0%, transparent 50%),
                radial-gradient(circle at 80% 80%, rgba(236, 72, 153, 0.1) 0%, transparent 50%);
    pointer-events: none;
    z-index: 0;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: var(--spacing-lg);
    position: relative;
    z-index: 1;
}

header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    padding-top: var(--spacing-lg);
}

h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    background: linear-gradient(135deg, var(--primary-light), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
}

.logo-icon {
    width: 48px;
    height: 48px;
    stroke: var(--primary);
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1.125rem;
    font-weight: 400;
}

/* Input Section */
.input-section {
    margin-bottom: var(--spacing-xl);
}

.input-wrapper {
    position: relative;
    margin-bottom: var(--spacing-sm);
}

.input-wrapper input {
    width: 100%;
    padding: 1.25rem 4rem 1.25rem 1.5rem;
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 2px solid var(--glass-border);
    border-radius: var(--radius-lg);
    color: var(--text-primary);
    font-size: 1rem;
    font-family: inherit;
    transition: all var(--transition-base);
    outline: none;
}

.input-wrapper input:focus {
    border-color: var(--primary);
    box-shadow: var(--shadow-glow);
}

.input-wrapper input::placeholder {
    color: var(--text-muted);
}

.input-icon {
    position: absolute;
    right: 1.5rem;
    top: 50%;
    transform: translateY(-50%);
    width: 24px;
    height: 24px;
    color: var(--text-muted);
    pointer-events: none;
}

.hint {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* Loading State */
.loading-state {
    text-align: center;
    padding: var(--spacing-xl);
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 2px solid var(--glass-border);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-lg);
}

.spinner {
    width: 48px;
    height: 48px;
    margin: 0 auto var(--spacing-sm);
    border: 4px solid var(--glass-border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

/* Error Message */
.error-message {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md);
    background: rgba(239, 68, 68, 0.1);
    backdrop-filter: blur(10px);
    border: 2px solid rgba(239, 68, 68, 0.3);
    border-radius: var(--radius-md);
    color: var(--error);
    margin-bottom: var(--spacing-lg);
}

.error-message svg {
    width: 24px;
    height: 24px;
    flex-shrink: 0;
}

/* Video Card */
.video-card {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 2px solid var(--glass-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
    box-shadow: var(--shadow-xl);
    animation: slideUp 0.4s ease;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.video-thumbnail {
    position: relative;
    width: 100%;
    border-radius: var(--radius-md);
    overflow: hidden;
    margin-bottom: var(--spacing-md);
    aspect-ratio: 16 / 9;
    background: var(--bg-secondary);
}

.video-thumbnail img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-slow);
}

.video-card:hover .video-thumbnail img {
    transform: scale(1.05);
}

.duration-badge {
    position: absolute;
    bottom: var(--spacing-sm);
    right: var(--spacing-sm);
    background: rgba(15, 23, 42, 0.9);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    font-weight: 600;
}

.video-info h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    line-height: 1.3;
}

.video-meta {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-bottom: var(--spacing-md);
}

.separator {
    color: var(--text-muted);
}

/* Progress Container */
.progress-container {
    margin: var(--spacing-md) 0;
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.progress-bar {
    width: 100%;
    height: 12px;
    background: var(--bg-secondary);
    border-radius: var(--radius-full);
    overflow: hidden;
    margin-bottom: var(--spacing-sm);
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.1);
}

.progress-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: var(--radius-full);
    transition: width 0.3s ease;
    position: relative;
    overflow: hidden;
}

.progress-fill::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    background: linear-gradient(
        90deg,
        transparent,
        rgba(255, 255, 255, 0.3),
        transparent
    );
    animation: shimmer 2s infinite;
}

@keyframes shimmer {
    0% { transform: translateX(-100%); }
    100% { transform: translateX(100%); }
}

.progress-text {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 600;
}

/* Download Button */
.download-btn {
    width: 100%;
    padding: 1rem 2rem;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 1.125rem;
    font-weight: 600;
    font-family: inherit;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    transition: all var(--transition-base);
    box-shadow: var(--shadow-lg);
}

.download-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl), var(--shadow-glow);
}

.download-btn:active {
    transform: translateY(0);
}

.download-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

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

/* Success Message */
.success-message {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md);
    background: rgba(16, 185, 129, 0.1);
    backdrop-filter: blur(10px);
    border: 2px solid rgba(16, 185, 129, 0.3);
    border-radius: var(--radius-md);
    color: var(--success);
    margin-top: var(--spacing-md);
    animation: fadeIn 0.3s ease;
}

.success-message svg {
    width: 24px;
    height: 24px;
    flex-shrink: 0;
}

/* Platforms Section */
.platforms-section {
    text-align: center;
    padding: var(--spacing-xl) 0;
}

.platforms-section h3 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

.platforms-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.platform-badge {
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
    transition: all var(--transition-base);
}

.platform-badge:hover {
    border-color: var(--primary);
    transform: translateY(-2px);
}

.platforms-note {
    color: var(--text-muted);
    font-size: 0.875rem;
    line-height: 1.8;
}

.platforms-note strong {
    color: var(--primary-light);
}

/* Utility Classes */
.hidden {
    display: none !important;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: var(--spacing-md);
    }
    
    h1 {
        font-size: 2rem;
        flex-direction: column;
    }
    
    .logo-icon {
        width: 40px;
        height: 40px;
    }
    
    .subtitle {
        font-size: 1rem;
    }
    
    .video-info h2 {
        font-size: 1.25rem;
    }
    
    .platforms-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}