intro-row: cap subtitle at 580px (was 720px) for tighter line length

static/index.html

@@ -61,7 +61,7 @@
      collapses to a single column. */
   .intro-row {
     display: grid;
-    grid-template-columns: minmax(0, 720px) auto;
+    grid-template-columns: minmax(0, 580px) auto;
     justify-content: start;
     gap: 28px;
     align-items: start;