Style Design Notes button with red glow animation

Replaces the secondary PF button style with a solid Red Hat red (#c9190b)
background and a pulsing box-shadow glow animation to make the button more
visually prominent in the fullscreen prototype view.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: matthewcarleton

hub/src/App.tsx

@@ -1364,6 +1364,7 @@ function HpuxPrototypesEmbedFullscreenPage() {
       icon={<OutlinedStickyNoteIcon aria-hidden />}
       onClick={() => setIsDesignNotesOpen((prev) => !prev)}
       aria-expanded={isDesignNotesOpen}
+      className="ops-hub-design-notes-btn"
     >
       Design Notes
     </Button>

hub/src/AppChrome.css

@@ -610,3 +610,21 @@ body.ops-hub-embed-fullscreen-active {
 .ops-hub-prototype-card--private__message-wrap {
   max-width: 100%;
 }
+
+/* Design Notes button — solid Red Hat red with pulsing glow */
+@keyframes design-notes-glow {
+  0%, 100% { box-shadow: 0 0 6px 2px rgba(201, 25, 11, 0.5); }
+  50% { box-shadow: 0 0 14px 5px rgba(201, 25, 11, 0.85); }
+}
+
+.ops-hub-design-notes-btn {
+  background-color: #c9190b !important;
+  color: #fff !important;
+  border-color: #c9190b !important;
+  animation: design-notes-glow 2s ease-in-out infinite;
+}
+
+.ops-hub-design-notes-btn:hover {
+  background-color: #a30000 !important;
+  border-color: #a30000 !important;
+}