<details>: go back to display: block

inline-block would cause consecutive <details> elements to end up next
to each other, but we want them to be on separate lines.

tildes/scss/_placeholders.scss

@@ -18,7 +18,7 @@
 
     &:not([open]) {
       cursor: pointer;
-      display: inline-block;
+      width: max-content;
     }
   }