3.9

Summaries added — every column in COL_DESCRIPTIONS got a short (1–2 sentences) and a link to its reference row. Full desc text kept intact for the day-tab metric labels.
Popup rewired — renders the summary plus a "More about this column →" link, opening in a new tab.
Link styling — .col-info-more pinned below the summary so it stays visible if the text scrolls; centred on mobile with the rest.
Anchors on the reference page — 35 row ids in columns.html, one per column key.
New "Rows" row — the hour/interval header had a popup but no matching row on the reference page; added.
Landing highlight — tr:target gets a gold bar and tint, with scroll offset so the nav doesn't cover it.

assets/about.css

@@ -318,6 +318,16 @@ em { color: #7a5c2a; font-style: italic; }
   color: #5a3e1a;
 }
 
+/* Deep-linked rows (from the in-app column-header popups) get a brief
+   highlight so the reader can see which one they landed on. */
+.col-ref-table tr[id] {
+  scroll-margin-top: 80px;
+}
+.col-ref-table tr:target td {
+  background: #fdf0cc;
+  box-shadow: inset 3px 0 0 #c8922a;
+}
+
 .faq-block {
   background: #fef8ea;
   border: 1px solid #e0d0a8;