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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.app-container {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    border-radius: 16px;
    padding: 30px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

header {
    text-align: center;
    margin-bottom: 30px;
}

h1 {
    font-size: 2em;
    color: #333;
    font-weight: 700;
}

/* Toolbar Styling */
.toolbar {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    padding: 20px;
    background: #f8f9fa;
    border-radius: 12px;
    margin-bottom: 30px;
    align-items: center;
}

.toolbar-group {
    display: flex;
    align-items: center;
    gap: 10px;
}

.toolbar-group label {
    font-weight: 600;
    color: #555;
    font-size: 0.9em;
}

#grid-size {
    padding: 8px 12px;
    border: 2px solid #ddd;
    border-radius: 6px;
    font-size: 1em;
    background: white;
    cursor: pointer;
    transition: border-color 0.2s;
}

#grid-size:hover {
    border-color: #667eea;
}

#color-picker {
    width: 60px;
    height: 40px;
    border: 2px solid #ddd;
    border-radius: 6px;
    cursor: pointer;
    background: none;
}

.color-palette {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
}

.color-swatch {
    width: 32px;
    height: 32px;
    border-radius: 6px;
    cursor: pointer;
    border: 3px solid transparent;
    transition: all 0.2s;
}

.color-swatch:hover {
    transform: scale(1.15);
    border-color: #333;
}

.color-swatch.active {
    border-color: #667eea;
    box-shadow: 0 0 0 2px white, 0 0 0 4px #667eea;
}

.bg-selector {
    display: flex;
    gap: 10px;
}

.bg-option {
    display: flex;
    align-items: center;
    gap: 5px;
    padding: 6px 12px;
    border: 2px solid #ddd;
    border-radius: 6px;
    cursor: pointer;
    background: white;
    transition: all 0.2s;
    font-size: 0.85em;
}

.bg-option:hover {
    border-color: #667eea;
}

.bg-option input[type="radio"] {
    cursor: pointer;
    accent-color: #667eea;
}

.bg-option input[type="radio"]:checked {
    accent-color: #667eea;
}

.bg-option:has(input:checked) {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

#output-size {
    width: 80px;
    padding: 8px 12px;
    border: 2px solid #ddd;
    border-radius: 6px;
    font-size: 1em;
    background: white;
    transition: border-color 0.2s;
}

#output-size:hover {
    border-color: #667eea;
}

#output-size:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.size-label {
    font-size: 0.85em;
    color: #555;
}

.tool-btn, .action-btn {
    padding: 10px 20px;
    border: 2px solid #ddd;
    border-radius: 8px;
    font-size: 0.95em;
    font-weight: 600;
    cursor: pointer;
    background: white;
    transition: all 0.2s;
}

.tool-btn:hover, .action-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.tool-btn.active {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

.action-btn.primary {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

.action-btn.primary:hover {
    background: #5568d3;
}

/* Canvas Container */
.canvas-container {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
    background: #f0f0f0;
    border-radius: 12px;
    min-height: 400px;
}

#pixel-grid {
    display: grid;
    gap: 0;
    background: white;
    border: 2px solid #333;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.2);
}

.pixel {
    aspect-ratio: 1;
    border: 1px solid #e0e0e0;
    cursor: pointer;
    background: white;
    transition: opacity 0.1s;
}

.pixel:hover {
    opacity: 0.8;
}

/* Responsive Design */
@media (max-width: 768px) {
    body {
        padding: 10px;
    }

    .app-container {
        padding: 20px;
    }

    h1 {
        font-size: 1.5em;
    }

    .toolbar {
        gap: 15px;
        padding: 15px;
    }

    .toolbar-group {
        flex-basis: 100%;
    }

    .canvas-container {
        padding: 10px;
        overflow-x: auto;
    }

    #pixel-grid {
        min-width: 280px;
        max-width: 100%;
    }
}

@media (max-width: 480px) {
    .app-container {
        padding: 15px;
    }

    .toolbar-group {
        gap: 8px;
    }

    .tool-btn, .action-btn {
        padding: 8px 16px;
        font-size: 0.85em;
    }

    .color-swatch {
        width: 28px;
        height: 28px;
    }
}