list.css

:root {
	--list-spacing: 1rem;

	--list-items-width: 13.25rem;
	--list-items-padding-right: 1rem;
	--list-items-border-width: 0.0625rem;

	--list-item-height: 1.75rem;
	--list-item-padding-top: 0.25rem;
	--list-item-padding-bottom: 0.25rem;
	--list-item-padding-left: 0.5rem;
	--list-item-padding-right: 0.5rem;
}

.cosmo-side-list {
	display: grid;
	grid-template-columns: [items-list] var(--list-items-width) var(--list-spacing) [content] 1fr;
	height: var(--page-height);
}

.cosmo-side-list__items {
	grid-column: items-list;
	display: flex;
	flex-flow: column;
	padding-right: var(--list-items-padding-right);
	border-right: var(--list-items-border-width) solid var(--control-border-color);
	box-sizing: border-box;
	height: var(--page-height);
	overflow-y: auto;
}

.cosmo-side-list__items .cosmo-button.is--full-width {
	margin-top: auto;
}

.cosmo-side-list__item {
	--list-item-color: var(--black);

	color: var(--list-item-color);
	padding: var(--list-item-padding-top) var(--list-item-padding-right)
		var(--list-item-padding-bottom) var(--list-item-padding-left);
	overflow-x: hidden;
	white-space: nowrap;
	text-overflow: ellipsis;
	width: 100%;
	box-sizing: border-box;
	cursor: pointer;
	min-height: var(--list-item-height);
	border-radius: var(--border-radius);
	background: var(--list-item-background);
	display: flex;
	align-items: center;
	text-decoration: none;
}

.cosmo-side-list__item:hover {
	--list-item-background: var(--control-border-color);
}

.cosmo-side-list__item.is--active,
.cosmo-side-list__item.is--active:hover {
	--list-item-background: var(--primary-color);
	--list-item-color: var(--white);

	font-weight: var(--font-weight-bold);
}

@media screen and (prefers-color-scheme: dark) {
	.cosmo-side-list__item.is--active,
	.cosmo-side-list__item.is--active:hover {
		--list-item-color: var(--black);
	}
}

.cosmo-side-list__item.is--active::selection,
.cosmo-side-list__item.is--active:hover::selection {
	--list-item-background: var(--white);
	--list-item-color: var(--primary-color);
}

.cosmo-side-list__content {
	grid-column: content;
	height: 100%;
	overflow-y: auto;
}