Indent subheads in TOC on all pages

docs/extra.css

@@ -83,5 +83,9 @@ h1, h2, h3, h4, h5, h6 {
     padding-top: 0.9em;
 }
 
+.toctree-l3 {
+  border-left: 10px solid transparent;
+}
+
 /* import font awesome 4 for icons */
 @import url(https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css);

docs/options.md

@@ -614,10 +614,6 @@ optional arguments:
 ```
 
 <style>
-  .toctree-l3 {
-    border-left: 10px solid transparent;
-  }
-
   .options-toc {
     display: grid;
     grid-auto-columns: fit-content(20%) 1fr;