OC mobile: make the floating CTA navy (amber border) so the bottom UI reads dark blue

The amber float-cta bar hugged the iOS address bar, making the bottom region read
orange (theme-color is already navy #0f1729). Recolor the floating button to navy
with an amber border — visible on both cream and navy sections, on-brand, and the
bottom region now matches the navy browser toolbar.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

style.css

@@ -337,7 +337,8 @@ a:focus-visible, .btn:focus-visible { outline: 2px solid var(--amber); outline-o
 /* Persistent CTA — returns after the hero scrolls off, steps aside at the contact */
 .float-cta { position: fixed; right: 22px; bottom: 22px; z-index: 80; opacity: 0; transform: translateY(12px); pointer-events: none; transition: opacity .35s ease, transform .35s ease; }
 .float-cta.show { opacity: 1; transform: none; pointer-events: auto; }
-.float-cta .btn { box-shadow: 0 6px 22px rgba(15, 23, 41, 0.18); }
+.float-cta .btn { background: #0f1729; color: #fff; border-color: var(--amber); box-shadow: 0 8px 24px rgba(15, 23, 41, 0.30); }
+.float-cta .btn:hover { background: #0b1220; border-color: var(--amber); }
 
 @media (prefers-reduced-motion: reduce) {
   .has-motion .reveal, .has-motion .stagger > * { opacity: 1; transform: none; }