docs site: scale headings with the viewport so the title stops breaking mid-word

At 360px wide the h1 was still 52px, because Material keeps a 20px root on mobile, so
"Cooperative" (297px at that size) left only ~30px of slack before breaking mid-word.

Headings now use clamp() to track the viewport and reach the same desktop sizes, with
word-break: normal, hyphens: none and text-wrap: balance so wrapping happens at the
space and the two lines are balanced rather than one word sitting alone.

publishing/typography.css

@@ -32,10 +32,31 @@ body,
   letter-spacing: -0.01em;
 }
 
-.md-typeset h1 { font-size: 2.6rem; font-weight: 700; letter-spacing: -0.02em; }
+.md-typeset h1,
-.md-typeset h2 { font-size: 1.7rem; font-weight: 600; }
+.md-typeset h2,
-.md-typeset h3 { font-size: 1.25rem; font-weight: 600; }
+.md-typeset h3,
-.md-header__title { font-weight: 600; }
+.md-typeset h4,
+.md-header__title {
+  /* Never break a word mid-way; wrap at the space, and let the browser balance the
+     two lines rather than leaving one word on its own. */
+  overflow-wrap: break-word;
+  word-break: normal;
+  hyphens: none;
+  text-wrap: balance;
+}
+
+/* Fluid scale. Fixed rem sizes do not shrink on a phone -- Material keeps a 20px root
+ * even at 360px wide -- so a 2.6rem h1 stays 52px and "Cooperative" (297px at that
+ * size) runs out of room on anything narrower than ~370px and breaks mid-word.
+ * These track the viewport instead and land at the same desktop size.
+ */
+.md-typeset h1 { font-size: clamp(1.6rem, 1.5rem + 3.2vw, 2.6rem); font-weight: 700; letter-spacing: -0.02em; }
+.md-typeset h2 { font-size: clamp(1.3rem, 1.1rem + 1.6vw, 1.7rem); font-weight: 600; }
+.md-typeset h3 { font-size: clamp(1.1rem, 1rem + 0.7vw, 1.25rem); font-weight: 600; }
+.md-header__title { font-size: clamp(0.85rem, 0.7rem + 0.8vw, 0.95rem); font-weight: 600; }
+
+/* Long prose stays readable; measured in characters rather than pixels. */
+.md-typeset { line-height: 1.65; }
 
 /* Colour is scheme-specific, so it stays out of the rules above. */
 [data-md-color-scheme="default"] .md-typeset h1,