:root {
    /* Premium Color Palette */
    --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, #11998e 0%, #38ef7d 100%);
    --danger-gradient: linear-gradient(135deg, #ff416c 0%, #ff4b2b 100%);
    
    /* Base Colors */
    --bg-dark: #0f0f1a;
    --bg-card: rgba(255, 255, 255, 0.03);
    --bg-card-hover: rgba(255, 255, 255, 0.06);
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.1);
    
    /* Text Colors */
    --text-primary: #ffffff;
    --text-secondary: rgba(255, 255, 255, 0.7);
    --text-muted: rgba(255, 255, 255, 0.4);
    
    /* Accent Colors */
    --accent-cyan: #00f2fe;
    --accent-purple: #667eea;
    --accent-pink: #f093fb;
    --accent-green: #38ef7d;
    
    /* Shadows */
    --shadow-sm: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 8px 25px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 20px 40px rgba(0, 0, 0, 0.3);
    --shadow-glow: 0 0 40px rgba(102, 126, 234, 0.3);
    
    /* Transitions */
    --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, sans-serif;
    background: var(--bg-dark);
    color: var(--text-primary);
    min-height: 100vh;
    overflow-x: hidden;
    position: relative;
}

/* Animated Background */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(ellipse at 20% 20%, rgba(102, 126, 234, 0.15) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 80%, rgba(240, 147, 251, 0.1) 0%, transparent 50%),
        radial-gradient(ellipse at 50% 50%, rgba(0, 242, 254, 0.05) 0%, transparent 70%);
    z-index: -1;
    animation: backgroundPulse 15s ease-in-out infinite;
}

@keyframes backgroundPulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.7; }
}

/* Main Container - Full Width */
.app-container {
    max-width: 1600px;
    margin: 0 auto;
    padding: 30px 24px;
    min-height: 100vh;
}

/* Header */
.header {
    text-align: center;
    margin-bottom: 30px;
}

.logo {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 8px;
}

.logo-icon {
    width: 48px;
    height: 48px;
    background: var(--primary-gradient);
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    box-shadow: var(--shadow-glow);
    animation: logoFloat 3s ease-in-out infinite;
}

@keyframes logoFloat {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-3px); }
}

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

.tagline {
    color: var(--text-secondary);
    font-size: 1rem;
    font-weight: 300;
}

/* Main Layout - Side by Side */
.main-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
    align-items: start;
}

.column {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.column-title {
    font-size: 0.85rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-muted);
    padding-bottom: 8px;
    border-bottom: 1px solid var(--glass-border);
    margin-bottom: 4px;
}

.column-title.input-title {
    color: var(--accent-purple);
}

.column-title.output-title {
    color: var(--accent-green);
}

/* Glass Card */
.glass-card {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: 20px;
    padding: 24px;
    transition: all var(--transition-normal);
}

.glass-card:hover {
    background: var(--bg-card-hover);
    border-color: rgba(255, 255, 255, 0.15);
}

/* Section Titles */
.section-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.section-title-icon {
    width: 28px;
    height: 28px;
    background: var(--primary-gradient);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
}

/* Upload Area - Compact */
.upload-zone {
    border: 2px dashed rgba(102, 126, 234, 0.4);
    border-radius: 16px;
    padding: 32px 24px;
    text-align: center;
    background: rgba(102, 126, 234, 0.05);
    transition: all var(--transition-normal);
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.upload-zone::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.1), transparent);
    transition: left 0.5s;
}

.upload-zone:hover::before {
    left: 100%;
}

.upload-zone:hover,
.upload-zone.dragover {
    border-color: var(--accent-cyan);
    background: rgba(0, 242, 254, 0.08);
    transform: scale(1.01);
}

.upload-icon {
    width: 60px;
    height: 60px;
    margin: 0 auto 16px;
    background: var(--primary-gradient);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 28px;
    box-shadow: var(--shadow-glow);
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); box-shadow: var(--shadow-glow); }
    50% { transform: scale(1.03); box-shadow: 0 0 50px rgba(102, 126, 234, 0.4); }
}

.upload-title {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 6px;
}

.upload-subtitle {
    color: var(--text-secondary);
    margin-bottom: 16px;
    font-size: 0.9rem;
}

.upload-btn {
    background: var(--primary-gradient);
    color: white;
    border: none;
    padding: 12px 28px;
    border-radius: 10px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-sm);
}

.upload-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.file-input {
    display: none;
}

.supported-formats {
    margin-top: 14px;
    color: var(--text-muted);
    font-size: 0.75rem;
}

/* Video Format Options */
.format-options {
    background: rgba(102, 126, 234, 0.1);
    border: 1px solid rgba(102, 126, 234, 0.3);
    border-radius: 14px;
    padding: 16px 20px;
    display: none;
    animation: slideIn 0.3s ease;
}

.format-options.visible {
    display: block;
}

@keyframes slideIn {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}

.format-options-title {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--accent-cyan);
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.format-checkboxes {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

.format-checkbox {
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    padding: 10px 16px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 10px;
    transition: all var(--transition-normal);
    font-size: 0.9rem;
}

.format-checkbox:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--accent-purple);
}

.format-checkbox.checked {
    background: rgba(102, 126, 234, 0.2);
    border-color: var(--accent-purple);
}

.format-checkbox input[type="checkbox"] {
    width: 18px;
    height: 18px;
    accent-color: var(--accent-purple);
    cursor: pointer;
}

.format-checkbox span {
    font-weight: 500;
}

.format-badge {
    font-size: 0.65rem;
    padding: 2px 6px;
    border-radius: 5px;
    background: var(--accent-gradient);
    color: var(--bg-dark);
    font-weight: 600;
    margin-left: 4px;
}

.format-hint {
    margin-top: 10px;
    font-size: 0.75rem;
    color: var(--text-muted);
}

/* File List */
.file-list {
    min-height: 80px;
    max-height: 400px;
    overflow-y: auto;
}

.file-list::-webkit-scrollbar {
    width: 6px;
}

.file-list::-webkit-scrollbar-track {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 3px;
}

.file-list::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.2);
    border-radius: 3px;
}

.file-list::-webkit-scrollbar-thumb:hover {
    background: rgba(255, 255, 255, 0.3);
}

.file-list-empty {
    color: var(--text-muted);
    text-align: center;
    padding: 24px;
    font-style: italic;
    font-size: 0.9rem;
}

.file-item {
    display: flex;
    flex-direction: column;
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid rgba(255, 255, 255, 0.06);
    border-radius: 12px;
    padding: 12px 14px;
    margin-bottom: 10px;
    transition: all var(--transition-normal);
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateX(-10px); }
    to { opacity: 1; transform: translateX(0); }
}

.file-item:hover {
    background: rgba(255, 255, 255, 0.06);
    border-color: rgba(255, 255, 255, 0.12);
}

.file-item-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    gap: 10px;
}

.file-info {
    display: flex;
    align-items: center;
    gap: 10px;
    flex: 1;
    min-width: 0;
}

.file-icon {
    width: 36px;
    height: 36px;
    border-radius: 9px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 16px;
    flex-shrink: 0;
}

.file-icon.image { background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); }
.file-icon.video { background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%); }
.file-icon.audio { background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%); }

.file-name {
    font-weight: 500;
    color: var(--text-primary);
    font-size: 0.9rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.file-actions {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-shrink: 0;
}

.quality-toggle {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 6px 10px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 6px;
    cursor: pointer;
    transition: all var(--transition-normal);
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.quality-toggle:hover {
    background: rgba(255, 255, 255, 0.1);
}

.quality-toggle.active {
    background: rgba(56, 239, 125, 0.2);
    border-color: var(--accent-green);
    color: var(--accent-green);
}

.quality-toggle input {
    accent-color: var(--accent-green);
    width: 14px;
    height: 14px;
}

/* Preview */
.file-preview {
    margin-top: 10px;
    padding-top: 10px;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.preview-media {
    max-width: 160px;
    max-height: 120px;
    border-radius: 10px;
    border: 2px solid rgba(255, 255, 255, 0.1);
    transition: all var(--transition-normal);
}

.preview-media:hover {
    border-color: var(--accent-purple);
    transform: scale(1.02);
}

.preview-label {
    font-size: 0.7rem;
    color: var(--text-muted);
    margin-top: 5px;
}

/* Action Buttons */
.action-bar {
    display: flex;
    gap: 12px;
    justify-content: center;
    flex-wrap: wrap;
    padding: 16px 0;
}

.btn {
    padding: 14px 28px;
    border: none;
    border-radius: 12px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
    display: inline-flex;
    align-items: center;
    gap: 8px;
    text-decoration: none;
}

.btn-primary {
    background: var(--success-gradient);
    color: white;
    box-shadow: 0 4px 20px rgba(56, 239, 125, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 25px rgba(56, 239, 125, 0.4);
}

.btn-danger {
    background: var(--danger-gradient);
    color: white;
    box-shadow: 0 4px 20px rgba(255, 65, 108, 0.3);
}

.btn-danger:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 25px rgba(255, 65, 108, 0.4);
}

.btn-download {
    background: var(--accent-gradient);
    color: var(--bg-dark);
    padding: 8px 14px;
    font-size: 0.8rem;
    border-radius: 8px;
}

.btn-download:hover {
    transform: translateY(-1px);
}

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

/* Loading Spinner */
.spinner-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(15, 15, 26, 0.9);
    backdrop-filter: blur(10px);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    flex-direction: column;
}

.spinner-overlay.visible {
    display: flex;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 3px solid rgba(255, 255, 255, 0.1);
    border-top-color: var(--accent-cyan);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

.spinner-text {
    margin-top: 16px;
    color: var(--text-secondary);
    font-size: 1rem;
}

/* Converted Files */
.converted-item {
    background: rgba(56, 239, 125, 0.05);
    border-color: rgba(56, 239, 125, 0.2);
}

.converted-item:hover {
    background: rgba(56, 239, 125, 0.1);
    border-color: rgba(56, 239, 125, 0.3);
}

/* Failed Files */
.failed-item {
    background: rgba(255, 65, 108, 0.05);
    border-color: rgba(255, 65, 108, 0.2);
}

.failed-item .file-icon {
    background: var(--danger-gradient);
}

.error-message {
    color: #ff6b8a;
    font-size: 0.8rem;
    margin-top: 3px;
}

/* Download All Button */
.download-all-container {
    text-align: center;
    margin-top: 16px;
    padding-top: 16px;
    border-top: 1px solid var(--glass-border);
}

.btn-download-all {
    background: var(--secondary-gradient);
    color: white;
    padding: 12px 24px;
    box-shadow: 0 4px 20px rgba(240, 147, 251, 0.3);
}

.btn-download-all:hover {
    box-shadow: 0 6px 25px rgba(240, 147, 251, 0.4);
}

/* Responsive */
@media (max-width: 1024px) {
    .main-layout {
        grid-template-columns: 1fr;
    }
    
    .app-container {
        padding: 20px 16px;
    }
}

@media (max-width: 768px) {
    .glass-card {
        padding: 18px;
    }
    
    .upload-zone {
        padding: 24px 16px;
    }
    
    .logo-text {
        font-size: 1.6rem;
    }
    
    .format-checkboxes {
        flex-direction: column;
        gap: 10px;
    }
    
    .action-bar {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
}

/* Animations */
.fade-in {
    animation: fadeIn 0.5s ease;
}

.slide-up {
    animation: slideUp 0.5s ease;
}

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