canvas {
    border: 2px solid black;
}

.btn-label {position: relative;left: -10px;padding: 6px 12px;background: rgba(0,0,0,0.15);border-radius: 3px 0 0 3px;}
.btn-labeled {padding-top: 0;padding-bottom: 0;}
.btn { margin-bottom:10px; }