made tips accept font size in URL query string via ?size=

doc/help.js

@@ -5,8 +5,7 @@
     // colored vertical bar running along it, to the left of the body. Links in
     // tips.html use this to open the help with the relevant part highlighted.
     function applyHighlighting() {
-        const params = new URLSearchParams(location.search);
-        const idToMark = params.get('highlight');
+        const idToMark = new URLSearchParams(location.search).get('highlight');
         if (idToMark === null) return;
 
         document.getElementById(idToMark).classList.add('highlighted');

doc/tips.html

@@ -9,6 +9,10 @@
     <link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=DM+Sans:wght@400;700&family=IBM+Plex+Mono:wght@700&display=swap">
     <link rel="stylesheet" href="shared.css">
     <link rel="stylesheet" href="tips.css">
+    <script src="https://unpkg.com/@ungap/[email protected]/min.js"
+            integrity="sha384-cduzXFJp9BFmTpHsZ9dKgXokrdxGJ5Ix5rWJdBihjdTpqdmtvn48NpDmTLwB79Bf"
+            crossorigin="anonymous"
+            defer></script>
     <script src="https://cdnjs.cloudflare.com/ajax/libs/classlist/1.2.20180112/classList.min.js"
             integrity="sha512-ISyiBXwG69Utm2wNP5ex+4P5+JmPaXmBMV82Uq/Yuck54FnOC4ZIJ9vDIT9TzHzZZC/xdYgivc2wmKuJkAZHmQ=="
             crossorigin="anonymous"

doc/tips.js

@@ -1,6 +1,12 @@
 (function () {
     'use strict';
 
+    // Set a body font size, if requested in the URL query string.
+    const size = new URLSearchParams(location.search).get('size');
+    if (size !== null) {
+        document.body.style.fontSize = size;
+    }
+
     // Whole-row items should navigate when clicked anywhere, not just in a
     // cell. We'll find the first link inside each and make clicking go there.
     const wholeRowItems = document.querySelectorAll('tr.item');