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

:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --secondary-color: #6b7280;
    --background-color: #f9fafb;
    --card-background: #ffffff;
    --border-color: #e5e7eb;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --success-color: #10b981;
    --shadow-sm: 0 1px 2px 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);
    --border-radius: 12px;
    --transition: all 0.2s ease;
}

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

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
header {
    text-align: center;
    padding: 40px 20px;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 10px;
}

.subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
}

/* Main Content */
main {
    flex: 1;
}

/* Upload Section */
.upload-section {
    margin-bottom: 30px;
}

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

.upload-area:hover,
.upload-area.dragover {
    border-color: var(--primary-color);
    background-color: #f0f0ff;
}

.upload-icon {
    width: 64px;
    height: 64px;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.upload-text {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.upload-subtext {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 12px;
}

.upload-formats {
    font-size: 0.875rem;
    color: var(--secondary-color);
}

/* Controls Section */
.controls-section {
    background: var(--card-background);
    border-radius: var(--border-radius);
    padding: 30px;
    margin-bottom: 30px;
    box-shadow: var(--shadow-md);
    display: flex;
    flex-wrap: wrap;
    gap: 30px;
    align-items: flex-start;
}

.control-group {
    flex: 1;
    min-width: 250px;
}

.control-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-primary);
}

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

.quality-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.quality-slider::-webkit-slider-thumb:hover {
    transform: scale(1.1);
}

.quality-slider::-moz-range-thumb {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    border: none;
    box-shadow: var(--shadow-md);
}

.quality-labels {
    display: flex;
    justify-content: space-between;
    margin-top: 8px;
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.format-select {
    width: 100%;
    padding: 12px 16px;
    font-size: 1rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    background: var(--card-background);
    color: var(--text-primary);
    cursor: pointer;
    transition: var(--transition);
}

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

/* Comparison Section */
.comparison-section {
    margin-bottom: 30px;
}

.comparison-container {
    display: flex;
    gap: 20px;
    background: var(--card-background);
    border-radius: var(--border-radius);
    padding: 30px;
    box-shadow: var(--shadow-md);
}

.image-panel {
    flex: 1;
    min-width: 0;
}

.image-panel h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.image-wrapper {
    background: #f3f4f6;
    border-radius: 8px;
    overflow: hidden;
    margin-bottom: 16px;
    aspect-ratio: 4/3;
    display: flex;
    align-items: center;
    justify-content: center;
}

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

.image-info {
    display: flex;
    justify-content: space-between;
    padding: 8px 0;
    border-bottom: 1px solid var(--border-color);
    font-size: 0.875rem;
}

.info-label {
    color: var(--text-secondary);
}

.info-value {
    font-weight: 600;
    color: var(--text-primary);
}

.divider {
    width: 2px;
    background: var(--border-color);
    margin: 0 10px;
}

/* Download Section */
.download-section {
    display: flex;
    gap: 16px;
    justify-content: center;
    margin-top: 30px;
    flex-wrap: wrap;
}

.download-btn,
.reset-btn {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 14px 28px;
    font-size: 1rem;
    font-weight: 600;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition);
}

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

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

.download-btn svg {
    width: 20px;
    height: 20px;
}

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

.reset-btn:hover {
    background: #d1d5db;
}

/* Footer */
footer {
    text-align: center;
    padding: 30px 20px;
    margin-top: auto;
    border-top: 1px solid var(--border-color);
}

footer p {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
}

footer a:hover {
    color: var(--primary-hover);
    text-decoration: underline;
}

/* Responsive Design */
@media (max-width: 768px) {
    header h1 {
        font-size: 1.75rem;
    }

    .subtitle {
        font-size: 1rem;
    }

    .upload-area {
        padding: 40px 20px;
    }

    .upload-icon {
        width: 48px;
        height: 48px;
    }

    .upload-text {
        font-size: 1.125rem;
    }

    .comparison-container {
        flex-direction: column;
        padding: 20px;
    }

    .divider {
        width: 100%;
        height: 2px;
        margin: 10px 0;
    }

    .controls-section {
        padding: 20px;
    }

    .control-group {
        min-width: 100%;
    }

    .download-section {
        flex-direction: column;
        align-items: stretch;
    }

    .download-btn,
    .reset-btn {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 10px;
    }

    header {
        padding: 20px 10px;
    }

    header h1 {
        font-size: 1.5rem;
    }

    .comparison-container {
        padding: 15px;
    }

    .image-wrapper {
        aspect-ratio: 1;
    }
}

/* Loading State */
.loading {
    opacity: 0.6;
    pointer-events: none;
}

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

.fade-in {
    animation: fadeIn 0.3s ease-out;
}