css: drop both display headings one size down

clamp 1.25-1.75rem -> 1.1-1.5rem; phone 1.15rem -> 1rem. Both headings
share the same values so they stay consistent.

app.py

@@ -417,7 +417,7 @@ gradio-app > div {
   margin: 0;
   font-family: "Source Serif 4", "Source Serif Pro", ui-serif, Georgia, serif;
   font-weight: 600;
-  font-size: clamp(1.25rem, 2vw, 1.75rem);
+  font-size: clamp(1.1rem, 1.8vw, 1.5rem);
   line-height: 1.2;
   letter-spacing: -0.01em;
   color: var(--q-text);
@@ -474,7 +474,7 @@ gradio-app > div {
   font-weight: 600 !important;
   /* Kept identical to .quest-header-title so the two display headings match
      in size and line spacing. */
-  font-size: clamp(1.25rem, 2vw, 1.75rem) !important;
+  font-size: clamp(1.1rem, 1.8vw, 1.5rem) !important;
   line-height: 1.2 !important;
   letter-spacing: -0.01em !important;
   text-transform: none !important;
@@ -1241,7 +1241,7 @@ footer { display: none !important; }
 @media (max-width: 600px) {
   .quest-header-title,
   .hero-heading {
-    font-size: 1.15rem !important;
+    font-size: 1rem !important;
     line-height: 1.2 !important;
   }
 }