/* Enhanced CSS Custom Properties for Dark Theme */
:root {
    /* Core Colors */
    --bg-primary: #0a0a0b;
    --bg-secondary: #1a1b23;
    --bg-tertiary: #2a2d3a;
    --bg-glass: rgba(42, 45, 58, 0.8);
    
    /* Text Colors */
    --text-primary: #ffffff;
    --text-secondary: #e2e8f0;
    --text-muted: #94a3b8;
    --text-accent: #f8fafc;
    
    /* Accent Colors */
    --accent-primary: #3b82f6;
    --accent-secondary: #1d4ed8;
    --accent-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --accent-glow: rgba(59, 130, 246, 0.3);
    
    /* Status Colors */
    --success: #10b981;
    --success-glow: rgba(16, 185, 129, 0.2);
    --warning: #f59e0b;
    --warning-glow: rgba(245, 158, 11, 0.2);
    --error: #ef4444;
    --error-glow: rgba(239, 68, 68, 0.2);
    
    /* Border & Effects */
    --border: #374151;
    --border-light: #4b5563;
    --border-glow: rgba(59, 130, 246, 0.5);
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 25px 50px -12px rgba(0, 0, 0, 0.6);
    --shadow-xl: 0 35px 60px -12px rgba(0, 0, 0, 0.7);
    --shadow-glow: 0 0 20px rgba(59, 130, 246, 0.3);
    --shadow-inner: inset 0 2px 4px 0 rgba(0, 0, 0, 0.3);
    
    /* Spacing & Typography */
    --radius: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    --spacing-2xl: 48px;
    --font-size-xs: 12px;
    --font-size-sm: 14px;
    --font-size-base: 16px;
    --font-size-lg: 18px;
    --font-size-xl: 20px;
    --font-size-2xl: 24px;
    --font-size-3xl: 30px;
    --font-size-4xl: 36px;
    
    /* Animations */
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    --bounce: cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

/* Reset and Base Styles */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

::selection {
    background: var(--accent-glow);
    color: var(--text-primary);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    background: var(--bg-primary);
    background-image: 
        radial-gradient(circle at 20% 50%, rgba(59, 130, 246, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(139, 92, 246, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 40% 80%, rgba(16, 185, 129, 0.05) 0%, transparent 50%);
    color: var(--text-primary);
    line-height: 1.6;
    font-size: var(--font-size-base);
    overflow-x: hidden;
    position: relative;
}

body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        linear-gradient(135deg, transparent 0%, rgba(59, 130, 246, 0.02) 50%, transparent 100%),
        radial-gradient(ellipse at top, rgba(59, 130, 246, 0.05) 0%, transparent 70%);
    pointer-events: none;
    z-index: -1;
}

/* Scrollbar Styling */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: var(--accent-primary);
    border-radius: 4px;
    transition: var(--transition);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-secondary);
}

/* Layout */
#app {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    position: relative;
}

.main-container {
    flex: 1;
    padding: var(--spacing-2xl);
    max-width: 1400px;
    margin: 0 auto;
    width: 100%;
    position: relative;
}

/* Enhanced Header */
.app-header {
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    padding: var(--spacing-lg) var(--spacing-2xl);
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow);
}

.app-header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: var(--accent-gradient);
    opacity: 0.3;
}

.app-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    font-size: var(--font-size-2xl);
    font-weight: 800;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-shadow: 0 0 30px var(--accent-glow);
}

.app-logo svg {
    width: 40px;
    height: 40px;
    filter: drop-shadow(0 0 10px var(--accent-glow));
}

.header-actions {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
}

/* Enhanced Upload Zone */
.upload-zone {
    background: var(--bg-secondary);
    background-image: 
        linear-gradient(45deg, transparent 25%, rgba(59, 130, 246, 0.02) 25%, rgba(59, 130, 246, 0.02) 50%, transparent 50%, transparent 75%, rgba(59, 130, 246, 0.02) 75%);
    background-size: 40px 40px;
    border: 2px dashed var(--border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-2xl);
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    transition: var(--transition);
    cursor: pointer;
    position: relative;
    overflow: hidden;
    min-height: 400px;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-inner);
}

.upload-zone::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--accent-gradient);
    opacity: 0;
    transition: var(--transition);
    border-radius: var(--radius-xl);
}

.upload-zone:hover {
    border-color: var(--accent-primary);
    box-shadow: var(--shadow-glow), var(--shadow-inner);
    transform: translateY(-2px);
}

.upload-zone:hover::before {
    opacity: 0.05;
}

.upload-zone.drag-over {
    border-color: var(--accent-primary);
    background: var(--bg-tertiary);
    transform: scale(1.02);
    box-shadow: var(--shadow-glow), 0 0 40px var(--accent-glow);
}

.upload-zone.drag-over::before {
    opacity: 0.1;
}

.upload-content {
    position: relative;
    z-index: 2;
    max-width: 600px;
}

/* Animated upload icon */
.upload-icon-container {
    position: relative;
    display: inline-block;
    margin-bottom: var(--spacing-lg);
}

.upload-icon {
    width: 80px;
    height: 80px;
    color: var(--accent-primary);
    filter: drop-shadow(0 0 20px var(--accent-glow));
    transition: var(--transition);
}

.upload-zone:hover .upload-icon {
    transform: translateY(-6px) scale(1.1);
    animation: float 3s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(-6px) scale(1.1); }
    50% { transform: translateY(-12px) scale(1.15); }
}

.upload-pulse {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 100px;
    height: 100px;
    background: var(--accent-primary);
    border-radius: 50%;
    opacity: 0.1;
    transform: translate(-50%, -50%);
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0% {
        transform: translate(-50%, -50%) scale(0.8);
        opacity: 0.2;
    }
    50% {
        transform: translate(-50%, -50%) scale(1.2);
        opacity: 0.05;
    }
    100% {
        transform: translate(-50%, -50%) scale(1.8);
        opacity: 0;
    }
}

.upload-title {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--text-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.upload-subtitle {
    color: var(--text-muted);
    margin-bottom: var(--spacing-xl);
    line-height: 1.8;
    font-size: var(--font-size-lg);
}

/* Enhanced Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    border: none;
    border-radius: var(--radius-lg);
    font-size: var(--font-size-sm);
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    min-height: 48px;
    position: relative;
    overflow: hidden;
    background-clip: padding-box;
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(45deg, transparent 30%, rgba(255, 255, 255, 0.1) 50%, transparent 70%);
    transform: translateX(-100%);
    transition: transform 0.6s;
}

.btn:hover::before {
    transform: translateX(100%);
}

.btn-primary {
    background: var(--accent-gradient);
    color: white;
    box-shadow: var(--shadow), 0 0 20px var(--accent-glow);
    border: 1px solid var(--accent-primary);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg), 0 0 30px var(--accent-glow);
}

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

.btn-secondary {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border);
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background: var(--bg-glass);
    border-color: var(--accent-primary);
    transform: translateY(-1px);
    box-shadow: var(--shadow);
}

.btn-large {
    padding: var(--spacing-lg) var(--spacing-2xl);
    font-size: var(--font-size-base);
    min-height: 56px;
    border-radius: var(--radius-xl);
    margin-bottom: 2em;
}

/* Enhanced Upload Actions */
.upload-actions {
    display: flex;
    gap: var(--spacing-lg);
    justify-content: center;
    margin-bottom: var(--spacing-xl);
    flex-wrap: wrap;
}

.btn-upload {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-xl);
    min-width: 160px;
    min-height: 100px;
    border-radius: var(--radius-xl);
    background: var(--bg-tertiary);
    border: 2px solid var(--border);
    transition: var(--transition);
}

.btn-upload:hover {
    border-color: var(--accent-primary);
    background: var(--bg-glass);
    transform: translateY(-4px);
    box-shadow: var(--shadow-glow);
}

.btn-text {
    font-weight: 700;
    font-size: var(--font-size-base);
}

.btn-shortcut {
    font-size: var(--font-size-xs);
    opacity: 0.7;
    font-weight: 400;
    color: var(--text-muted);
}

/* Format Tags */
.supported-formats {
    display: flex;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-lg);
    flex-wrap: wrap;
}

.format-tag {
    background: var(--bg-glass);
    backdrop-filter: blur(10px);
    color: var(--accent-primary);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: 20px;
    font-size: var(--font-size-xs);
    font-weight: 600;
    border: 1px solid var(--border);
    transition: var(--transition);
}

.format-tag:hover {
    background: var(--accent-primary);
    color: white;
    transform: scale(1.05);
}

/* Enhanced Icons */
.icon {
    width: 24px;
    height: 24px;
    fill: currentColor;
    transition: var(--transition);
}

.btn:hover .icon {
    transform: scale(1.1);
}

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

.glass {
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border: 1px solid var(--border);
}

.glow {
    box-shadow: var(--shadow-glow);
}

.gradient-text {
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Animation Classes */
.animate-in {
    animation: slideInUp 0.6s var(--bounce);
}

@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in {
    animation: fadeIn 0.5s ease-out;
}

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

/* Enhanced Responsive Design */
@media (max-width: 768px) {
    .main-container {
        padding: var(--spacing-lg);
    }
    
    .app-header {
        padding: var(--spacing-md) var(--spacing-lg);
    }
    
    .upload-zone {
        padding: var(--spacing-xl);
        min-height: 300px;
    }
    
    .upload-title {
        font-size: var(--font-size-2xl);
    }
    
    .upload-actions {
        flex-direction: column;
        align-items: stretch;
    }
    
    .btn-upload {
        flex-direction: row;
        justify-content: center;
        min-height: 60px;
        min-width: auto;
    }
    
    .upload-icon {
        width: 60px;
        height: 60px;
    }
}

@media (max-width: 480px) {
    .app-logo {
        font-size: var(--font-size-xl);
    }
    
    .upload-icon {
        width: 48px;
        height: 48px;
    }
    
    .upload-title {
        font-size: var(--font-size-xl);
    }
    
    .main-container {
        padding: var(--spacing-md);
    }
}

/* Accessibility Improvements */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --bg-primary: #000000;
        --bg-secondary: #1a1a1a;
        --text-primary: #ffffff;
        --border: #666666;
        --accent-primary: #4a9eff;
    }
}

/* Focus states for accessibility */
.btn:focus-visible,
.upload-zone:focus-visible {
    outline: 2px solid var(--accent-primary);
    outline-offset: 2px;
}