Details hover style

The element(s) you want to add scrollbar(s) should have the typical CSS properties of an overflowed block which are a height (or max-height) value, an overflow value of auto (or hidden) and content long enough to require scrolling. For horizontal scrollbar, the element should have a width (or max-width) value set. If you prefer to set your element’s height/width via javascript, you can use the setHeight/setWidth option parameters.