/* CSS Custom Properties */
:root {
    --primary-color: #4285f4;
    --primary-hover: #3367d6;
    --secondary-color: #f8f9fa;
    --text-primary: #202124;
    --text-secondary: #5f6368;
    --border-color: #dadce0;
    --border-radius: 8px;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 4px 20px rgba(0, 0, 0, 0.15);
    --success-color: #34a853;
    --danger-color: #ea4335;
    --warning-color: #fbbc04;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

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

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: #ffffff;
}

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

/* Header Styles */
header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 60px 0;
    text-align: center;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 20px;
}

.header-text {
    flex: 1;
    text-align: left;
}

.header-actions {
    display: flex;
    align-items: center;
}

.donate-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: rgba(255, 255, 255, 0.2);
    color: white;
    padding: 12px 24px;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.3);
}

.donate-btn:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
}

.donate-btn svg {
    width: 16px;
    height: 16px;
    stroke-width: 2.5;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 16px;
}

.subtitle {
    font-size: 1.2rem;
    font-weight: 300;
    opacity: 0.9;
    max-width: 600px;
    margin: 0 auto;
}

/* Main Content */
main {
    padding: 60px 0;
}

/* Upload Section */
.upload-section {
    margin-bottom: 40px;
}

.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: var(--border-radius);
    padding: 60px 40px;
    text-align: center;
    background: var(--secondary-color);
    transition: all 0.3s ease;
    cursor: pointer;
}

.upload-area:hover {
    border-color: var(--primary-color);
    background: #f0f7ff;
}

.upload-area.dragover {
    border-color: var(--primary-color);
    background: #e3f2fd;
    transform: scale(1.02);
}

.upload-icon {
    color: var(--primary-color);
    margin-bottom: 20px;
}

.upload-area h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.upload-area p {
    color: var(--text-secondary);
    margin-bottom: 24px;
}

.browse-btn {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

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

/* Loading Spinner */
.loading-spinner {
    display: none;
    text-align: center;
    padding: 40px;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 20px;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Compression Section */
.compression-section {
    display: none;
    background: white;
    border-radius: var(--border-radius);
    padding: 40px;
    box-shadow: var(--shadow);
    margin-bottom: 40px;
}

.controls {
    margin-bottom: 30px;
}

.quality-control {
    margin-bottom: 20px;
}

.quality-control label {
    display: block;
    font-weight: 500;
    margin-bottom: 8px;
    color: var(--text-primary);
}

#qualitySlider {
    width: 100%;
    height: 8px;
    border-radius: 4px;
    background: var(--border-color);
    outline: none;
    -webkit-appearance: none;
    appearance: none;
}

#qualitySlider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    box-shadow: var(--shadow);
}

#qualitySlider::-moz-range-thumb {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    border: none;
    box-shadow: var(--shadow);
}

.file-info {
    background: var(--secondary-color);
    padding: 20px;
    border-radius: var(--border-radius);
}

.size-info {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    justify-content: space-between;
}

.size-info span {
    font-weight: 500;
    font-size: 0.9rem;
}

.original-size {
    color: var(--text-secondary);
}

.compressed-size {
    color: var(--primary-color);
}

.savings {
    color: var(--success-color);
}

/* Preview Container */
.preview-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
    margin-bottom: 30px;
}

.preview-item h3 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 12px;
    text-align: center;
    color: var(--text-primary);
}

.image-container {
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    overflow: hidden;
    background: var(--secondary-color);
    height: 300px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.image-container img {
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
}

/* Actions */
.actions {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

.download-btn {
    background: var(--success-color);
    color: white;
    border: none;
    padding: 14px 28px;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 8px;
}

.download-btn:hover {
    background: #2e7d32;
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.reset-btn {
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
    padding: 14px 28px;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.reset-btn:hover {
    background: var(--secondary-color);
    color: var(--text-primary);
}

/* FAQ Section */
.faq-section {
    margin-bottom: 40px;
}

.faq-section h2 {
    text-align: center;
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 40px;
    color: var(--text-primary);
}

.faq-container {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    background: white;
    border-radius: var(--border-radius);
    margin-bottom: 16px;
    box-shadow: var(--shadow);
    overflow: hidden;
    transition: all 0.3s ease;
}

.faq-item:hover {
    box-shadow: var(--shadow-hover);
}

.faq-question {
    width: 100%;
    padding: 20px 24px;
    background: none;
    border: none;
    text-align: left;
    cursor: pointer;
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--text-primary);
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: all 0.3s ease;
}

.faq-question:hover {
    background: var(--secondary-color);
}

.faq-question:focus {
    outline: none;
    background: var(--secondary-color);
}

.faq-icon {
    color: var(--primary-color);
    transition: transform 0.3s ease;
    flex-shrink: 0;
    margin-left: 16px;
}

.faq-item.active .faq-icon {
    transform: rotate(180deg);
}

.faq-answer {
    padding: 0 24px;
    max-height: 0;
    overflow: hidden;
    transition: all 0.3s ease;
}

.faq-item.active .faq-answer {
    max-height: 500px;
    padding: 0 24px 24px;
}

.faq-answer p {
    color: var(--text-secondary);
    line-height: 1.6;
    margin: 0;
}

/* Info Section */
.info-section {
    margin-bottom: 40px;
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-top: 40px;
}

.info-item {
    background: white;
    padding: 30px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.info-item h3 {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.info-item p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Footer */
footer {
    background: var(--secondary-color);
    padding: 40px 0;
    border-top: 1px solid var(--border-color);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 20px;
}

.privacy-note {
    flex: 1;
    min-width: 300px;
}

.privacy-note p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.footer-links {
    text-align: right;
}

.footer-links p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 8px;
}

.links {
    display: flex;
    gap: 16px;
}

.links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    transition: color 0.3s ease;
}

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

/* Responsive Design */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        text-align: center;
    }
    
    .header-text {
        text-align: center;
    }
    
    header h1 {
        font-size: 2rem;
    }
    
    .subtitle {
        font-size: 1rem;
    }
    
    .donate-btn {
        padding: 10px 20px;
        font-size: 0.9rem;
    }
    
    .upload-area {
        padding: 40px 20px;
    }
    
    .compression-section {
        padding: 30px 20px;
    }
    
    .preview-container {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .size-info {
        flex-direction: column;
        gap: 10px;
    }
    
    .actions {
        flex-direction: column;
        align-items: stretch;
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
    }
    
    .footer-links {
        text-align: center;
    }
    
    .info-grid {
        grid-template-columns: 1fr;
    }
    
    .faq-section h2 {
        font-size: 1.8rem;
    }
    
    .faq-question {
        font-size: 1rem;
        padding: 16px 20px;
    }
    
    .faq-answer {
        padding: 0 20px;
    }
    
    .faq-item.active .faq-answer {
        padding: 0 20px 20px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    header {
        padding: 40px 0;
    }
    
    main {
        padding: 40px 0;
    }
    
    .upload-area {
        padding: 30px 15px;
    }
    
    .compression-section {
        padding: 20px 15px;
    }
    
    .info-item {
        padding: 20px;
    }
    
    .faq-section h2 {
        font-size: 1.6rem;
        margin-bottom: 30px;
    }
    
    .faq-question {
        font-size: 0.95rem;
        padding: 14px 16px;
    }
    
    .faq-answer {
        padding: 0 16px;
    }
    
    .faq-item.active .faq-answer {
        padding: 0 16px 16px;
    }
    
    .faq-icon {
        width: 20px;
        height: 20px;
        margin-left: 12px;
    }
}

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

.visible {
    display: block !important;
}

.flex {
    display: flex !important;
}