body { margin: 0; padding: 0; font-family: sans-serif; background: #f0f0f0; overflow: hidden; }
#ui {
    position: absolute; top: 10px; left: 10px;
    background: rgba(255,255,255,0.9); padding: 15px;
    border-radius: 8px; box-shadow: 0 2px 10px rgba(0,0,0,0.2);
    pointer-events: auto; width: 280px;
}
h2 { margin: 0 0 10px 0; font-size: 18px; }
.controls { font-size: 14px; line-height: 1.6; margin-bottom: 15px; color: #333; }
.key { font-weight: bold; background: #ddd; padding: 2px 5px; border-radius: 4px; }
button {
    display: block; width: 100%; padding: 10px; margin-bottom: 5px;
    cursor: pointer; border: 1px solid #ccc; background: #fff; text-align: left;
    transition: background 0.2s;
}
button:hover { background: #e0efff; }
button.active { background: #007bff; color: white; border-color: #0056b3; }
canvas { display: block; cursor: crosshair; }