.histogram-bar {
	transition: opacity 0.2s ease;
}
.histogram-bar.grayed {
	fill: #ccc !important;
	opacity: 0.5;
}
.drag-selection {
	fill: rgba(255, 255, 255, 0.3);
	stroke: #007bff;
	stroke-width: 2;
	stroke-dasharray: 4,4;
}