Fix the scrolling-away of the top toolbar

The height of the ContentLayout's container needs to match the height of its children for overscrolling and sticky behaviors to work as intended. It also needs to have a minimum of 100% so that it fills the height of its parent.

src/lib/components/layouts/ContentLayout.svelte

@@ -24,6 +24,8 @@
     align-self: stretch;
     position: relative;
     width: 100%;
+    height: fit-content;
+    min-height: 100%;
   }
   header {
     flex: 0 0 0;