body {
    font-family: Arial, sans-serif;
}
#toolbar {
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}
.tool-btn {
    transition: background 0.2s;
}
#whiteboard-canvas {
    margin-top: 20px;
    box-shadow: 0 4px 16px rgba(0,0,0,0.08);
}