mediawiki-extensions-VisualEditor/modules/ve-mw/ui/styles/elements/ve.ui.MWExpandableContentElement.less

.ve-ui-expandableContent {
	&-collapsible {
		overflow: hidden;
		position: relative;
		margin: 0.4em 0 0.5em 0;
		transition: height 200ms;
	}

	&-container {
		display: flex;
		align-items: center;
		position: absolute;
		bottom: 0;
		pointer-events: none; /* Allows clicking "through" the fade effect */
	}

	&-toggle {
		background-color: #fff;
		pointer-events: auto;
	}

	&-fade {
		background: linear-gradient( to right, rgba( 255, 255, 255, 0 ) 0, #fff 90% );
		width: 50px;
		height: 100%;
	}

	&-collapsible > :last-child {
		margin-bottom: 0;
	}
}