/* CSS Variables */
:root {
    /* Colors */
    --primary: #6366f1;
    --primary-hover: #4f46e5;
    --primary-light: rgba(99, 102, 241, 0.1);
    --secondary: #8b5cf6;
    --secondary-hover: #7c3aed;
    --success: #10b981;
    --success-light: rgba(16, 185, 129, 0.1);
    --error: #ef4444;
    --error-light: rgba(239, 68, 68, 0.1);
    --warning: #f59e0b;
    --warning-light: rgba(245, 158, 11, 0.1);
    --info: #3b82f6;
    --info-light: rgba(59, 130, 246, 0.1);
    
    /* Neutrals */
    --white: #ffffff;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    --black: #000000;
    
    /* Layout */
    --max-width: 1200px;
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    
    /* 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), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
    
    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.375rem;
    --radius-lg: 0.5rem;
    --radius-xl: 0.75rem;
    --radius-full: 9999px;
}

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--gray-900);
    background: linear-gradient(135deg, var(--gray-50) 0%, var(--white) 100%);
    min-height: 100vh;
}

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

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* Loading Screen */
.loading-screen {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--white);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 9999;
}

.spinner {
    width: 48px;
    height: 48px;
    border: 3px solid var(--gray-200);
    border-top-color: var(--primary);
    border-radius: var(--radius-full);
    animation: spin 1s linear infinite;
}

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

.loading-screen p {
    margin-top: var(--spacing-lg);
    color: var(--gray-600);
    font-size: var(--font-size-lg);
}

/* Header */
.app-header {
    background: var(--white);
    border-bottom: 1px solid var(--gray-200);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
}

.app-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg) var(--spacing-lg);
}

.app-title {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

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

.username {
    color: var(--gray-700);
    font-weight: 500;
}

/* Main Content */
.main-content {
    padding: var(--spacing-2xl) 0;
    min-height: calc(100vh - 140px);
}

/* Upload Section */
.upload-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-2xl);
}

.upload-card {
    background: var(--white);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
}

.section-title {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--gray-800);
    margin-bottom: var(--spacing-lg);
}

/* Drop Zone */
.drop-zone {
    border: 2px dashed var(--gray-300);
    border-radius: var(--radius-lg);
    padding: var(--spacing-2xl);
    text-align: center;
    transition: all var(--transition-base);
    cursor: pointer;
    background: var(--gray-50);
}

.drop-zone:hover {
    border-color: var(--primary);
    background: var(--primary-light);
}

.drop-zone.dragover {
    border-color: var(--primary);
    background: var(--primary-light);
    transform: scale(1.02);
}

.drop-zone.has-file {
    border-color: var(--success);
    background: var(--success-light);
}

.upload-icon {
    color: var(--gray-400);
    margin-bottom: var(--spacing-md);
}

.drop-text {
    font-size: var(--font-size-lg);
    color: var(--gray-700);
    margin-bottom: var(--spacing-xs);
}

.drop-hint {
    font-size: var(--font-size-sm);
    color: var(--gray-500);
}

/* Preview Containers */
.preview-container,
.preview-grid {
    margin-top: var(--spacing-lg);
}

.preview-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-md);
}

.preview-item {
    position: relative;
    border-radius: var(--radius-lg);
    overflow: hidden;
    background: var(--gray-100);
    aspect-ratio: 1;
}

.preview-item img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.preview-remove {
    position: absolute;
    top: var(--spacing-sm);
    right: var(--spacing-sm);
    width: 28px;
    height: 28px;
    border-radius: var(--radius-full);
    background: rgba(0, 0, 0, 0.6);
    color: var(--white);
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.preview-remove:hover {
    background: var(--error);
    transform: scale(1.1);
}

/* Upload Status Indicators */
.upload-status {
    position: absolute;
    bottom: var(--spacing-sm);
    right: var(--spacing-sm);
    width: 32px;
    height: 32px;
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
}

.upload-status.loading {
    background: rgba(99, 102, 241, 0.9);
}

.upload-status.success {
    background: rgba(16, 185, 129, 0.9);
    color: var(--white);
    font-size: 18px;
}

.upload-status.error {
    background: rgba(239, 68, 68, 0.9);
    color: var(--white);
    font-size: 18px;
}

.spinner-small {
    width: 16px;
    height: 16px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-top-color: var(--white);
    border-radius: var(--radius-full);
    animation: spin 0.6s linear infinite;
}

/* Buttons */
.btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-base);
    font-weight: 500;
    border: none;
    cursor: pointer;
    transition: all var(--transition-base);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    position: relative;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-hover) 100%);
    color: var(--white);
}

.btn-primary:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: var(--gray-100);
    color: var(--gray-700);
}

.btn-secondary:hover:not(:disabled) {
    background: var(--gray-200);
}

.btn-loader {
    width: 16px;
    height: 16px;
    border: 2px solid var(--white);
    border-top-color: transparent;
    border-radius: var(--radius-full);
    animation: spin 0.6s linear infinite;
}

/* Actions Section */
.actions {
    display: flex;
    justify-content: center;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.actions .btn {
    min-width: 150px;
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: var(--font-size-lg);
}

/* Results Section */
.results {
    background: var(--white);
    border-radius: var(--radius-xl);
    padding: var(--spacing-2xl);
    box-shadow: var(--shadow-lg);
    margin-bottom: var(--spacing-2xl);
}

.result-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xl);
}

.result-image {
    max-width: 100%;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
}

.result-image img {
    width: 100%;
    height: auto;
    display: block;
}

.result-actions {
    display: flex;
    gap: var(--spacing-md);
}

/* Footer */
.app-footer {
    background: var(--gray-900);
    color: var(--gray-400);
    padding: var(--spacing-lg) 0;
    text-align: center;
}

/* Notifications */
.notification-container {
    position: fixed;
    top: var(--spacing-xl);
    right: var(--spacing-xl);
    z-index: 1000;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.notification {
    min-width: 300px;
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

.notification.success {
    background: var(--success);
    color: var(--white);
}

.notification.error {
    background: var(--error);
    color: var(--white);
}

.notification.warning {
    background: var(--warning);
    color: var(--white);
}

.notification.info {
    background: var(--info);
    color: var(--white);
}

/* Responsive Design */
@media (max-width: 768px) {
    .upload-section {
        grid-template-columns: 1fr;
    }
    
    .preview-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .app-header .container {
        flex-direction: column;
        gap: var(--spacing-md);
        text-align: center;
    }
    
    .actions {
        flex-direction: column;
    }
    
    .actions .btn {
        width: 100%;
    }
    
    .notification-container {
        left: var(--spacing-md);
        right: var(--spacing-md);
        top: var(--spacing-md);
    }
    
    .notification {
        min-width: auto;
    }
}

/* Loading States */
.loading {
    position: relative;
    pointer-events: none;
    opacity: 0.6;
}

.loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 24px;
    height: 24px;
    margin: -12px 0 0 -12px;
    border: 2px solid var(--primary);
    border-top-color: transparent;
    border-radius: var(--radius-full);
    animation: spin 0.6s linear infinite;
}

/* Accessibility */
.btn:focus,
.drop-zone:focus {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

/* Print Styles */
@media print {
    .app-header,
    .app-footer,
    .actions,
    .upload-section {
        display: none;
    }
}