docs: align top-level nav pages and the API Reference label flush left

Top-level pages outside any section kept the pill's left padding plus a
stock margin, sitting 14px right of the section labels; pull their box
left by the pill inset so text lines up and the active pill overhangs the
gutter. The API Reference label (the one section without an index page,
rendered as a label element rather than a container div) was still caught
by the density rule via :not() specificity — exclude section items from
the density rules outright instead of relying on source order.

Author: maxisbey

docs/extra.css

@@ -11,13 +11,14 @@
      and active highlight, just denser. Group rows that link to an index
      page wrap their anchor in an .md-nav__container div whose stock
      padding is 0 — densify the inner anchor, not the wrapper. The
-     section-label rules below must come AFTER these: they win the
-     specificity tie on source order. */
-  .md-sidebar--primary .md-nav__item > .md-nav__link:not(.md-nav__container) {
+     section items are excluded outright: their label is styled by the
+     section rules below, and the :not() classes here would otherwise
+     out-rank those on specificity. */
+  .md-sidebar--primary .md-nav__item:not(.md-nav__item--section) > .md-nav__link:not(.md-nav__container) {
     padding: 4px 10px;
     margin-top: 2px;
   }
-  .md-sidebar--primary .md-nav__item > .md-nav__container {
+  .md-sidebar--primary .md-nav__item:not(.md-nav__item--section) > .md-nav__container {
     margin-top: 2px;
   }
   .md-sidebar--primary .md-nav__container > .md-nav__link {
@@ -34,7 +35,7 @@
   .md-sidebar--primary .md-nav__item--section > .md-nav__link {
     margin-top: 0;
     margin-left: 0;
-    padding-left: 0;
+    padding: 2px 0;
     font-size: 0.62rem;
     font-weight: 700;
     text-transform: uppercase;
@@ -63,6 +64,14 @@
     font-weight: 700;
   }
 
+  /* Top-level pages outside any section (the homepage entry, Protocol
+     versions, Troubleshooting, ...) share the left edge with the section
+     labels: pull the link box left by its own pill padding, so the text
+     is flush and the hover/active pill overhangs into the gutter. */
+  .md-sidebar--primary .md-nav--primary > .md-nav__list > .md-nav__item:not(.md-nav__item--section) > .md-nav__link:not(.md-nav__container) {
+    margin-inline-start: -10px;
+  }
+
   /* The sidebar repeats the site name right above the homepage nav entry;
      drop the title row on desktop (the mobile drawer still needs it for its
      drill-down back-navigation, hence the media-query scope). */