refactor: clean the sidebar up a little bit

public/base.css

@@ -96,6 +96,35 @@ select {
 	font-size: inherit;
 }
 
+details > summary {
+	display: block;
+	position: relative;
+	padding-left: 2rem;
+	cursor: pointer;
+	user-select: none;
+}
+
+details > summary:before {
+	content: "";
+	border-width: 0.6rem;
+	border-style: solid;
+	border-color: transparent transparent transparent rgba(from var(--border-subtle) r g b / 0.9);
+	position: absolute;
+	top: 0.15rem;
+	left: 0;
+	transform: rotate(0);
+	transform-origin: 0.3rem 50%;
+	transition: 0.25s transform ease;
+}
+
+details[open] > summary:before {
+	transform: rotate(90deg);
+}
+
+details > summary::-webkit-details-marker {
+	display: none;
+}
+
 form input,
 form textarea {
 	width: 100%;