:root {
    --bg-primary: #f5f5f5;
    --bg-secondary: #fff;
    --bg-tertiary: #fff;
    --text-primary: #333;
    --text-secondary: #666;
    --text-tertiary: #222;
    --border-color: #e0e0e0;
    --border-hover: #999;
    --shadow: rgba(0, 0, 0, 0.05);
    --accent: #333;
}

body.dark-theme {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-tertiary: #252525;
    --text-primary: #e0e0e0;
    --text-secondary: #b0b0b0;
    --text-tertiary: #f0f0f0;
    --border-color: #404040;
    --border-hover: #666;
    --shadow: rgba(0, 0, 0, 0.3);
    --accent: #4a9eff;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    height: 100vh;
    display: flex;
    flex-direction: column;
    transition: background-color 0.3s ease, color 0.3s ease;
}

header {
    background-color: var(--bg-secondary);
    padding: 1rem 2rem;
    border-bottom: 1px solid var(--border-color);
    box-shadow: 0 2px 4px var(--shadow);
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

header h1 {
    font-size: 1.5rem;
    font-weight: 500;
    color: var(--text-tertiary);
}

.theme-toggle {
    background: none;
    border: 2px solid var(--border-color);
    border-radius: 4px;
    padding: 0.5rem;
    cursor: pointer;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
}

.theme-toggle:hover {
    border-color: var(--border-hover);
    background-color: var(--bg-primary);
    color: var(--text-primary);
}

.container {
    display: flex;
    flex: 1;
    overflow: hidden;
}

.control-panel {
    width: 200px;
    background-color: var(--bg-secondary);
    padding: 1.5rem;
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    gap: 2rem;
    overflow-y: auto;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.control-panel h2 {
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.control-section {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.control-section label {
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-weight: 400;
}

.tool-buttons {
    display: flex;
    gap: 0.5rem;
}

.tool-btn {
    flex: 1;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    background-color: var(--bg-secondary);
    cursor: pointer;
    border-radius: 4px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.1s ease;
    color: var(--text-secondary);
}

.tool-btn:hover {
    border-color: var(--border-hover);
    background-color: var(--bg-primary);
}

.tool-btn.active {
    border-color: var(--accent);
    background-color: var(--accent);
    color: #fff;
}

#colorPicker,
#bgColorPicker {
    width: 100%;
    height: 50px;
    border: 2px solid var(--border-color);
    border-radius: 4px;
    cursor: pointer;
    padding: 0;
    background: none;
    transition: border-color 0.2s ease;
}

#colorPicker:hover,
#bgColorPicker:hover {
    border-color: var(--border-hover);
}

#brushSize {
    width: 100%;
    cursor: pointer;
    accent-color: var(--accent);
}

#brushSizeValue {
    color: var(--text-primary);
    font-weight: 500;
}

.drawing-area {
    flex: 1;
    background-color: var(--bg-tertiary);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
    transition: background-color 0.3s ease;
}

#drawingCanvas {
    background-color: #fff;
    border: 1px solid var(--border-color);
    cursor: crosshair;
    display: block;
    max-width: 100%;
    max-height: 100%;
    transition: border-color 0.3s ease;
}