:root {
    --primary: #4361ee;
    --primary-dark: #3a56d4;
    --primary-light: rgba(67, 97, 238, 0.1);
    --secondary: #7209b7;
    --secondary-light: rgba(114, 9, 183, 0.1);
    --accent: #f72585;
    --accent-light: rgba(247, 37, 133, 0.1);
    --success: #4cc9f0;
    --success-light: rgba(76, 201, 240, 0.1);
    --light: #f8f9fa;
    --dark: #212529;
    --gray: #6c757d;
    --light-gray: #e9ecef;
    --border-radius: 16px;
    --border-radius-sm: 8px;
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
    --shadow-hover: 0 20px 40px rgba(0, 0, 0, 0.12);
    --shadow-large: 0 25px 50px rgba(0, 0, 0, 0.15);
    --transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.1);
    --gradient-primary: linear-gradient(135deg, var(--primary), var(--secondary));
    --gradient-accent: linear-gradient(135deg, var(--accent), var(--secondary));
    --gradient-dark: linear-gradient(135deg, var(--dark), #000);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background-color: white;
    color: var(--dark);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.hidden {
    display: none !important;
}

/* Header */
header {
    background: white;
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.05);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: 16px 0;
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
}

.logo img {
    height: 40px;
    width: auto;
}

.mobile-menu {
    display: none;
    font-size: 1.5rem;
    color: var(--gray);
    cursor: pointer;
}

.nav-menu ul {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-menu a {
    text-decoration: none;
    color: var(--dark);
    font-weight: 500;
    font-size: 0.95rem;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: var(--transition);
    padding: 8px 0;
    position: relative;
}

.nav-menu a:hover {
    color: var(--primary);
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary);
    transition: width 0.3s ease;
}

.nav-menu a:hover::after {
    width: 100%;
}

.auth-buttons {
    display: flex;
    gap: 12px;
}

/* Buttons */
.btn {
    padding: 10px 24px;
    border-radius: var(--border-radius-sm);
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    transition: var(--transition);
    border: 2px solid transparent;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    white-space: nowrap;
}

.btn-outline {
    background: transparent;
    border-color: var(--primary);
    color: var(--primary);
}

.btn-outline:hover {
    background: var(--primary-light);
    transform: translateY(-2px);
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    border: none;
    position: relative;
    overflow: hidden;
}

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

.btn-primary::after {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.6s ease;
}

.btn-primary:hover::after {
    left: 100%;
}

.btn-secondary {
    background: white;
    color: var(--dark);
    border: 2px solid var(--light-gray);
    padding: 12px 32px;
    border-radius: var(--border-radius);
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.btn-secondary:hover {
    border-color: var(--primary);
    background: var(--primary-light);
    transform: translateY(-2px);
}

.btn-enhance {
    padding: 12px 48px;
    font-size: 1.1rem;
    border-radius: var(--border-radius);
}

/* Hero Section */
.hero {
    padding: 60px 0 40px;
    position: relative;
    overflow: hidden;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
    padding: 0 20px;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 20px;
    background: linear-gradient(135deg, var(--dark) 0%, var(--gray) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

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

.hero p {
    font-size: 1.2rem;
    color: var(--gray);
    max-width: 600px;
    margin: 0 auto 40px;
    line-height: 1.6;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 40px;
    margin-top: 40px;
    flex-wrap: wrap;
}

.stat {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 16px 24px;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.stat:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
}

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

.stat h3 {
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: 4px;
}

.stat p {
    font-size: 0.9rem;
    color: var(--gray);
    margin: 0;
}

.hero-illustration {
    display: none;
}

/* Main Tool */
.main-content {
    flex: 1;
    padding-bottom: 60px;
}

.tool-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Upload Section */
.upload-section {
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-large);
    padding: 40px;
    margin-bottom: 30px;
    transition: var(--transition);
}

.upload-area {
    border: 3px dashed var(--light-gray);
    border-radius: var(--border-radius);
    padding: 60px 40px;
    text-align: center;
    transition: var(--transition);
    cursor: pointer;
}

.upload-area:hover {
    border-color: var(--primary);
    background: var(--primary-light);
    transform: translateY(-2px);
}

.upload-area i {
    font-size: 4rem;
    color: var(--primary);
    margin-bottom: 20px;
    display: block;
}

.upload-area h3 {
    font-size: 1.8rem;
    margin-bottom: 12px;
    color: var(--dark);
}

.upload-area p {
    color: var(--gray);
    margin-bottom: 30px;
}

#browseBtn {
    padding: 14px 32px;
    font-size: 1.1rem;
    border-radius: var(--border-radius);
}

/* Preview Section */
.preview-section {
    margin-top: 40px;
    animation: fadeIn 0.5s ease;
}

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

.image-comparison {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    gap: 30px;
    align-items: start;
}

.image-container {
    background: white;
    border-radius: var(--border-radius);
    padding: 20px;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.image-container:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
}

.image-container h4 {
    font-size: 1.2rem;
    margin-bottom: 16px;
    color: var(--dark);
    display: flex;
    align-items: center;
    gap: 8px;
}

.image-wrapper {
    position: relative;
    border-radius: var(--border-radius-sm);
    overflow: hidden;
    margin-bottom: 12px;
    aspect-ratio: 16/9;
    background: var(--light-gray);
}

.image-wrapper img {
    width: 100%;
    height: 100%;
    object-fit: contain;
    display: block;
}

.enhanced-badge {
    position: absolute;
    top: 12px;
    right: 12px;
    background: var(--gradient-primary);
    color: white;
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 6px;
}

.image-info {
    display: flex;
    justify-content: space-between;
    color: var(--gray);
    font-size: 0.9rem;
}

.comparison-controls {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
    padding-top: 40px;
}

.compare-btn {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: white;
    border: 2px solid var(--light-gray);
    color: var(--primary);
    font-size: 1.2rem;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
}

.compare-btn:hover {
    background: var(--primary);
    color: white;
    transform: rotate(90deg);
}

.slider-container {
    width: 100%;
    transform: rotate(-90deg);
    padding: 20px 0;
}

#comparisonSlider {
    width: 100%;
    height: 6px;
    background: var(--light-gray);
    border-radius: 3px;
    outline: none;
    -webkit-appearance: none;
    appearance: none;
}

#comparisonSlider::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 24px;
    height: 24px;
    background: var(--primary);
    border-radius: 50%;
    cursor: pointer;
    border: 3px solid white;
    box-shadow: var(--shadow);
}

.slider-labels {
    display: flex;
    justify-content: space-between;
    margin-top: 40px;
    font-size: 0.9rem;
    color: var(--gray);
    transform: rotate(90deg);
}

/* Controls Section */
.controls-section {
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    padding: 40px;
    margin-bottom: 30px;
}

.enhancement-options {
    margin-bottom: 40px;
}

.enhancement-options h3 {
    font-size: 1.5rem;
    margin-bottom: 24px;
    color: var(--dark);
    display: flex;
    align-items: center;
    gap: 10px;
}

.option-group {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 16px;
    margin-bottom: 32px;
}

.option-label {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 16px;
    background: white;
    border: 2px solid var(--light-gray);
    border-radius: var(--border-radius-sm);
    cursor: pointer;
    transition: var(--transition);
    position: relative;
}

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

.option-label input[type="checkbox"] {
    display: none;
}

.custom-checkbox {
    width: 22px;
    height: 22px;
    border: 2px solid var(--light-gray);
    border-radius: 6px;
    transition: var(--transition);
    position: relative;
}

.option-label input[type="checkbox"]:checked + .custom-checkbox {
    background: var(--primary);
    border-color: var(--primary);
}

.option-label input[type="checkbox"]:checked + .custom-checkbox::after {
    content: '✓';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: white;
    font-weight: bold;
}

.option-content {
    flex: 1;
}

.option-content h4 {
    font-size: 1rem;
    margin-bottom: 4px;
    color: var(--dark);
}

.option-content p {
    font-size: 0.85rem;
    color: var(--gray);
}

.option-label i {
    color: var(--primary);
    font-size: 1.2rem;
}

.slider-option {
    background: white;
    padding: 24px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.slider-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 16px;
}

.slider-header h4 {
    font-size: 1.1rem;
    color: var(--dark);
    display: flex;
    align-items: center;
    gap: 8px;
}

#strengthValue {
    font-weight: 700;
    color: var(--primary);
    font-size: 1.2rem;
}

#strengthSlider {
    width: 100%;
    height: 8px;
    background: linear-gradient(to right, var(--light-gray), var(--primary));
    border-radius: 4px;
    outline: none;
    -webkit-appearance: none;
    appearance: none;
    margin: 20px 0;
}

#strengthSlider::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 28px;
    height: 28px;
    background: white;
    border-radius: 50%;
    cursor: pointer;
    border: 3px solid var(--primary);
    box-shadow: var(--shadow);
}

.slider-marks {
    display: flex;
    justify-content: space-between;
    color: var(--gray);
    font-size: 0.9rem;
}

.action-buttons {
    display: flex;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
}

/* Features Grid */
.features-section {
    padding: 60px 0 0;
}

.features-section h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 50px;
    color: var(--dark);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.feature-card {
    background: white;
    padding: 32px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
    text-align: center;
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-hover);
}

.feature-icon {
    width: 70px;
    height: 70px;
    background: var(--primary-light);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 24px;
}

.feature-icon i {
    font-size: 2rem;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.feature-card h3 {
    font-size: 1.3rem;
    margin-bottom: 12px;
    color: var(--dark);
}

.feature-card p {
    color: var(--gray);
    line-height: 1.6;
}

/* Footer */
footer {
    background: var(--dark);
    color: white;
    padding: 60px 0 30px;
    margin-top: auto;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-column h3 {
    color: white;
    margin-bottom: 20px;
    font-size: 1.2rem;
}

.footer-column p {
    color: rgba(255, 255, 255, 0.7);
    line-height: 1.6;
    margin-bottom: 20px;
}

.footer-column ul {
    list-style: none;
}

.footer-column ul li {
    margin-bottom: 12px;
}

.footer-column ul li a {
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-column ul li a:hover {
    color: white;
}

.social-icons {
    display: flex;
    gap: 12px;
    margin-top: 20px;
}

.social-icon {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.1);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    text-decoration: none;
    transition: var(--transition);
}

.social-icon:hover {
    background: var(--primary);
    transform: translateY(-3px);
}

.copyright {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.5);
    font-size: 0.9rem;
}

/* Dark Mode Toggle */
.dark-mode-toggle {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--gradient-primary);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-shadow: var(--shadow);
    transition: var(--transition);
    z-index: 999;
}

.dark-mode-toggle:hover {
    transform: scale(1.1) rotate(30deg);
}

/* Loading Overlay */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.95);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    backdrop-filter: blur(10px);
}

.loading-content {
    text-align: center;
    max-width: 500px;
    padding: 40px;
}

.spinner {
    width: 80px;
    height: 80px;
    border: 5px solid var(--light-gray);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 30px;
}

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

.loading-content h3 {
    font-size: 1.8rem;
    margin-bottom: 12px;
    color: var(--dark);
}

.loading-content p {
    color: var(--gray);
    margin-bottom: 30px;
}

.progress-bar {
    width: 100%;
    height: 6px;
    background: var(--light-gray);
    border-radius: 3px;
    overflow: hidden;
    margin: 30px 0;
}

.progress-fill {
    height: 100%;
    background: var(--gradient-primary);
    width: 0%;
    animation: progress 2s ease-in-out infinite alternate;
}

@keyframes progress {
    0% { width: 0%; }
    100% { width: 100%; }
}

.loading-tip {
    font-size: 0.9rem;
    color: var(--gray);
    font-style: italic;
}

/* Toast Notifications */
.toast-container {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 1001;
    display: flex;
    flex-direction: column;
    gap: 10px;
    max-width: 350px;
}

/* Disabled States */
button:disabled,
button[disabled] {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none !important;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .hero h1 {
        font-size: 2.8rem;
    }
    
    .image-comparison {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .comparison-controls {
        flex-direction: row;
        justify-content: center;
        padding-top: 0;
    }
    
    .slider-container {
        transform: none;
        padding: 0;
        width: auto;
    }
    
    .slider-labels {
        transform: none;
        margin-top: 10px;
    }
}

@media (max-width: 768px) {
    .header-content {
        flex-wrap: wrap;
    }
    
    .nav-menu {
        order: 3;
        flex: 1 0 100%;
        margin-top: 20px;
        display: none;
    }
    
    .nav-menu.active {
        display: block;
    }
    
    .nav-menu ul {
        flex-direction: column;
        gap: 0;
    }
    
    .nav-menu a {
        padding: 12px 0;
        border-bottom: 1px solid var(--light-gray);
    }
    
    .mobile-menu {
        display: block;
    }
    
    .auth-buttons {
        margin-left: auto;
    }
    
    .hero h1 {
        font-size: 2.2rem;
    }
    
    .hero-stats {
        flex-direction: column;
        align-items: center;
        gap: 15px;
    }
    
    .stat {
        width: 100%;
        max-width: 300px;
    }
    
    .upload-section,
    .controls-section {
        padding: 25px;
    }
    
    .option-group {
        grid-template-columns: 1fr;
    }
    
    .action-buttons {
        flex-direction: column;
    }
    
    .action-buttons button {
        width: 100%;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .social-icons {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .container,
    .tool-container {
        padding: 0 15px;
    }
    
    .hero h1 {
        font-size: 1.8rem;
    }
    
    .hero p {
        font-size: 1rem;
    }
    
    .upload-area {
        padding: 40px 20px;
    }
    
    .upload-area i {
        font-size: 3rem;
    }
    
    .upload-area h3 {
        font-size: 1.4rem;
    }
    
    .image-container {
        padding: 15px;
    }
    
    .enhancement-options h3 {
        font-size: 1.3rem;
    }
    
    .btn-enhance {
        padding: 12px 24px;
        font-size: 1rem;
    }
}

/* Print Styles */
@media print {
    header,
    .controls-section,
    .features-section,
    footer,
    .dark-mode-toggle {
        display: none;
    }
    
    .main-content {
        padding: 0;
    }
    
    .image-comparison {
        grid-template-columns: 1fr 1fr;
        gap: 20px;
    }
    
    .comparison-controls {
        display: none;
    }
}