Responsive base font size via svmin, not fixed 17px

Scales with viewport instead of capping at a fixed px value.
svmin (small-viewport min) rather than plain vmin - plain viewport
units recalculate as mobile Safari's address bar hides/shows on
scroll, which would reflow every text size mid-scroll; svmin stays
pinned to the smallest viewport state, matching the stability
.hero-yes already gets from 100svh.

style/main.css

@@ -45,6 +45,17 @@
   --sans: -apple-system, "SF Pro Text", ui-sans-serif, "Segoe UI", system-ui, sans-serif;
 
   --radius: 1.1rem;
+
+  /* responsive base size: scales with viewport (2.1svmin) on top of a
+     fixed floor (3pt) so it keeps growing on large/wide screens
+     instead of capping at a fixed px value like the old 17px did;
+     max(12px, ...) keeps it from shrinking below legible on tiny
+     viewports. svmin (small-viewport min), not plain vmin - plain vh
+     -based units recalculate as mobile Safari's address bar
+     hides/shows on scroll, which would reflow every text size on the
+     page mid-scroll; svmin stays fixed to the smallest viewport state,
+     same stability .hero-yes already gets from 100svh below. */
+  font-size: max(12px, calc(2.1svmin + 3pt));
 }
 
 * { box-sizing: border-box; }
@@ -55,7 +66,6 @@ html, body {
   background: var(--paper);
   color: var(--ink);
   font-family: var(--sans);
-  font-size: 17px;
   line-height: 1.55;
 }