:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary: #10b981;
    --secondary-hover: #059669;
    --background: #f8fafc;
    --surface: #ffffff;
    --surface-elevated: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border: #e2e8f0;
    --border-focus: #2563eb;
    --error: #ef4444;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --radius: 12px;
    --radius-sm: 8px;
    --radius-lg: 16px;
    --transition: all 0.2s ease;
}

*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

.header {
    text-align: center;
    padding: 48px 0 32px;
}

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

.logo svg {
    color: var(--primary);
}

.logo h1 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
}

.tagline {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

.main-content {
    display: flex;
    flex-direction: column;
    gap: 32px;
    padding-bottom: 48px;
}

.upload-section {
    width: 100%;
}

.drop-zone {
    position: relative;
    border: 2px dashed var(--border);
    border-radius: var(--radius-lg);
    background: var(--surface);
    padding: 64px 32px;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
}

.drop-zone:hover, .drop-zone.drag-over {
    border-color: var(--primary);
    background: #eff6ff;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.drop-zone-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
}

.upload-icon {
    color: var(--primary);
    opacity: 0.7;
    transition: var(--transition);
}

.drop-zone:hover .upload-icon {
    opacity: 1;
    transform: translateY(-4px);
}

.drop-zone-content h2 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

.drop-zone-content p {
    color: var(--text-secondary);
}

.file-types {
    display: inline-block;
    background: #eff6ff;
    color: var(--primary);
    padding: 6px 16px;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
}

.drop-zone input[type="file"] {
    position: absolute;
    inset: 0;
    opacity: 0;
    cursor: pointer;
}

.settings-section {
    width: 100%;
}

.settings-panel {
    background: var(--surface);
    border-radius: var(--radius-lg);
    padding: 32px;
    box-shadow: var(--shadow-md);
}

.settings-panel h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 24px;
    color: var(--text-primary);
}

.settings-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 24px;
    margin-bottom: 24px;
}

.setting-item {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.setting-item label {
    font-weight: 500;
    color: var(--text-primary);
    font-size: 0.95rem;
}

.setting-item input[type="range"] {
    width: 100%;
    height: 8px;
    border-radius: 4px;
    background: var(--border);
    outline: none;
    -webkit-appearance: none;
    cursor: pointer;
}

.setting-item input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary);
    cursor: pointer;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.setting-item input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.1);
}

.setting-item select {
    padding: 12px 16px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 1rem;
    color: var(--text-primary);
    background: var(--surface);
    cursor: pointer;
    transition: var(--transition);
}

.setting-item select:focus {
    outline: none;
    border-color: var(--primary);
}

.compress-btn {
    width: 100%;
    padding: 16px 32px;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    transition: var(--transition);
}

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

.compress-btn:disabled {
    background: var(--border);
    color: var(--text-secondary);
    cursor: not-allowed;
}

.results-section {
    display: none;
    width: 100%;
}

.results-section.active {
    display: block;
    animation: fadeIn 0.3s ease;
}

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

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

.results-header h3 {
    font-size: 1.25rem;
    font-weight: 600;
}

.clear-btn {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 16px;
    background: transparent;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-size: 0.9rem;
    cursor: pointer;
    transition: var(--transition);
}

.clear-btn:hover {
    border-color: var(--error);
    color: var(--error);
}

.results-stats {
    display: flex;
    gap: 24px;
    margin-bottom: 24px;
}

.stat-item {
    background: var(--surface);
    padding: 16px 24px;
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-sm);
}

.stat-label {
    display: block;
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 4px;
}

.stat-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--secondary);
}

.results-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 20px;
}

.result-card {
    background: var(--surface);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.result-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.result-preview {
    position: relative;
    height: 180px;
    background: #f1f5f9;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    cursor: pointer;
}

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

.result-preview-overlay {
    position: absolute;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: var(--transition);
}

.result-preview:hover .result-preview-overlay {
    opacity: 1;
}

.result-preview-overlay span {
    color: white;
    font-weight: 500;
    font-size: 0.9rem;
}

.result-details {
    padding: 20px;
}

.result-filename {
    font-weight: 600;
    margin-bottom: 12px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.result-stats {
    display: flex;
    justify-content: space-between;
    margin-bottom: 16px;
}

.result-original, .result-compressed {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.result-original span:first-child, .result-compressed span:first-child {
    font-size: 0.75rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.result-original span:last-child {
    font-size: 0.95rem;
    color: var(--text-secondary);
    text-decoration: line-through;
}

.result-compressed span:last-child {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--secondary);
}

.result-saved {
    display: inline-block;
    background: #ecfdf5;
    color: var(--secondary);
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}

.result-actions {
    display: flex;
    gap: 12px;
    margin-top: 16px;
}

.download-btn {
    flex: 1;
    padding: 12px 20px;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: var(--transition);
}

.download-btn:hover {
    background: var(--primary-hover);
}

.content-section {
    max-width: 800px;
    margin: 0 auto 48px;
    padding: 0 24px;
}

.content-block {
    background: var(--surface);
    border-radius: var(--radius-lg);
    padding: 40px;
    box-shadow: var(--shadow-md);
}

.content-block h2 {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 20px;
    line-height: 1.3;
}

.content-block h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin: 32px 0 16px;
    padding-top: 16px;
    border-top: 1px solid var(--border);
}

.content-block h3:first-of-type {
    margin-top: 24px;
    border-top: none;
    padding-top: 0;
}

.content-block p {
    color: var(--text-secondary);
    margin-bottom: 16px;
    line-height: 1.7;
}

.content-block ul {
    list-style: none;
    margin: 16px 0;
}

.content-block ul li {
    color: var(--text-secondary);
    padding: 8px 0;
    padding-left: 24px;
    position: relative;
    line-height: 1.6;
}

.content-block ul li::before {
    content: "";
    position: absolute;
    left: 0;
    top: 16px;
    width: 8px;
    height: 8px;
    background: var(--secondary);
    border-radius: 50%;
}

.content-block ul li strong {
    color: var(--text-primary);
}

.faq-item {
    margin-bottom: 24px;
    padding: 20px;
    background: #f8fafc;
    border-radius: var(--radius-sm);
    border-left: 4px solid var(--primary);
}

.faq-item h4 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 12px;
}

.faq-item p {
    margin-bottom: 0;
    font-size: 0.95rem;
}

.footer {
    text-align: center;
    padding: 32px 0;
    border-top: 1px solid var(--border);
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.preview-modal {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.8);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    padding: 24px;
}

.preview-modal.active {
    display: flex;
    animation: fadeIn 0.2s ease;
}

.preview-content {
    background: var(--surface);
    border-radius: var(--radius-lg);
    max-width: 900px;
    width: 100%;
    max-height: 90vh;
    overflow: auto;
    position: relative;
}

.close-preview {
    position: absolute;
    top: 16px;
    right: 16px;
    background: rgba(0, 0, 0, 0.5);
    border: none;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: white;
    transition: var(--transition);
    z-index: 10;
}

.close-preview:hover {
    background: rgba(0, 0, 0, 0.7);
}

.preview-comparison {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
    padding: 24px;
}

.preview-image {
    text-align: center;
}

.preview-image h4 {
    font-size: 1rem;
    margin-bottom: 16px;
    color: var(--text-secondary);
}

.preview-image img {
    width: 100%;
    max-height: 300px;
    object-fit: contain;
    border-radius: var(--radius-sm);
    background: #f1f5f9;
}

.preview-size {
    margin-top: 12px;
    font-weight: 600;
    font-size: 1.1rem;
}

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

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

@media (max-width: 768px) {
    .header {
        padding: 32px 0 24px;
    }

    .logo h1 {
        font-size: 1.5rem;
    }

    .tagline {
        font-size: 1rem;
    }

    .drop-zone {
        padding: 48px 24px;
    }

    .settings-panel {
        padding: 24px;
    }

    .results-stats {
        flex-direction: column;
    }

    .results-grid {
        grid-template-columns: 1fr;
    }

    .preview-comparison {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 16px;
    }

    .drop-zone {
        padding: 40px 16px;
    }

    .drop-zone-content h2 {
        font-size: 1.25rem;
    }

    .settings-grid {
        grid-template-columns: 1fr;
    }

    .compress-btn {
        padding: 14px 24px;
        font-size: 1rem;
    }

    .content-section {
        padding: 0 16px;
    }

    .content-block {
        padding: 24px;
    }

    .content-block h2 {
        font-size: 1.4rem;
    }

    .content-block h3 {
        font-size: 1.1rem;
    }

    .faq-item {
        padding: 16px;
    }
}