:root {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-tertiary: #3a3a3a;
    --text-primary: #ffffff;
    --text-secondary: #b0b0b0;
    --accent: #4a9eff;
    --accent-hover: #5fb0ff;
    --border: #404040;
    --success: #4ade80;
    --shadow: rgba(0, 0, 0, 0.3);
}

@media (prefers-color-scheme: light) {
    :root {
        --bg-primary: #ffffff;
        --bg-secondary: #f5f5f5;
        --bg-tertiary: #e8e8e8;
        --text-primary: #1a1a1a;
        --text-secondary: #666666;
        --accent: #2563eb;
        --accent-hover: #3b82f6;
        --border: #d0d0d0;
        --success: #22c55e;
        --shadow: rgba(0, 0, 0, 0.1);
    }
}

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

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

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
    width: 100%;
    flex: 1;
}

header {
    text-align: center;
    margin-bottom: 3rem;
}

h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--accent), #a855f7);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

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

/* Upload Section */
.upload-section {
    margin-bottom: 2rem;
}

.upload-area {
    border: 3px dashed var(--border);
    border-radius: 12px;
    padding: 4rem 2rem;
    text-align: center;
    background: var(--bg-secondary);
    transition: all 0.3s ease;
    cursor: pointer;
}

.upload-area:hover {
    border-color: var(--accent);
    background: var(--bg-tertiary);
    transform: translateY(-2px);
    box-shadow: 0 8px 16px var(--shadow);
}

.upload-area.dragover {
    border-color: var(--accent);
    background: var(--bg-tertiary);
    transform: scale(1.02);
}

.upload-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
}

.upload-icon {
    width: 64px;
    height: 64px;
    color: var(--accent);
    stroke-width: 2;
}

.upload-text {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-primary);
}

.upload-subtext {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

/* Settings Section */
.settings-section {
    background: var(--bg-secondary);
    border-radius: 12px;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 4px 12px var(--shadow);
}

.settings-section h2 {
    margin-bottom: 1.5rem;
    font-size: 1.5rem;
}

.settings-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.setting-item {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.setting-item label {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-weight: 500;
    color: var(--text-primary);
}

.value-display {
    color: var(--accent);
    font-weight: 600;
    font-size: 0.9rem;
}

.slider {
    width: 100%;
    height: 6px;
    border-radius: 3px;
    background: var(--bg-tertiary);
    outline: none;
    -webkit-appearance: none;
    appearance: none;
}

.slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--accent);
    cursor: pointer;
    transition: all 0.2s ease;
}

.slider::-webkit-slider-thumb:hover {
    background: var(--accent-hover);
    transform: scale(1.2);
}

.slider::-moz-range-thumb {
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--accent);
    cursor: pointer;
    border: none;
    transition: all 0.2s ease;
}

.slider::-moz-range-thumb:hover {
    background: var(--accent-hover);
    transform: scale(1.2);
}

.slider-labels {
    display: flex;
    justify-content: space-between;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* Toggle Switch */
.toggle-label {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    cursor: pointer;
}

.toggle-input {
    display: none;
}

.toggle-slider {
    position: relative;
    width: 50px;
    height: 26px;
    background: var(--bg-tertiary);
    border-radius: 26px;
    transition: background 0.3s ease;
}

.toggle-slider::before {
    content: '';
    position: absolute;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--text-primary);
    top: 3px;
    left: 3px;
    transition: transform 0.3s ease;
}

.toggle-input:checked + .toggle-slider {
    background: var(--accent);
}

.toggle-input:checked + .toggle-slider::before {
    transform: translateX(24px);
}

.toggle-text {
    font-weight: 500;
}

.setting-description {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: -0.5rem;
}

/* Format Select */
.format-select {
    width: 100%;
    padding: 0.75rem;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text-primary);
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.2s ease;
}

.format-select:hover {
    border-color: var(--accent);
}

.format-select:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(74, 158, 255, 0.1);
}

/* Preview Section */
.preview-section {
    background: var(--bg-secondary);
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 4px 12px var(--shadow);
}

.preview-section h2 {
    margin-bottom: 1.5rem;
    font-size: 1.5rem;
}

.preview-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.preview-item {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.preview-item h3 {
    font-size: 1.1rem;
    color: var(--text-secondary);
    text-align: center;
}

.preview-item canvas {
    width: 100%;
    height: auto;
    border-radius: 8px;
    background: var(--bg-primary);
    box-shadow: 0 2px 8px var(--shadow);
    image-rendering: pixelated;
    max-width: 100%;
}

#previewCanvas {
    image-rendering: pixelated;
}

/* Download Section */
.download-section {
    text-align: center;
}

.download-btn {
    background: linear-gradient(135deg, var(--accent), #a855f7);
    color: white;
    border: none;
    padding: 1rem 2.5rem;
    font-size: 1.1rem;
    font-weight: 600;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px var(--shadow);
}

.download-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px var(--shadow);
}

.download-btn:active {
    transform: translateY(0);
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }

    h1 {
        font-size: 2rem;
    }

    .upload-area {
        padding: 3rem 1.5rem;
    }

    .settings-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    .preview-container {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    .download-btn {
        width: 100%;
        padding: 1rem;
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 1.75rem;
    }

    .subtitle {
        font-size: 1rem;
    }

    .settings-section,
    .preview-section {
        padding: 1.5rem;
    }
}