sticky folders

website/src/lib/components/explorer/sticky.ts

@@ -0,0 +1,11 @@
+/** The height of a row of the explorer. */
+export const rowHeight = 28;
+
+/**
+ * The style of the row of a folder that is `depth` folders deep (0 for the open folder), to stick
+ * under the rows of the folders it is in while any of its content can be seen: the rows of the
+ * folders above are above it too.
+ */
+export function stickyRowStyle(depth: number): string {
+    return `top: ${depth * rowHeight}px; height: ${rowHeight}px; z-index: ${Math.max(100 - depth, 1)};`;
+}