starting refactor styling

web/vue-app/src/assets/button-shared.css

@@ -93,10 +93,57 @@
   font-weight: 600;
   margin-left: 6px;
 }
-.btn-link.btn-disabled {
+.btn-link:disabled {
   text-decoration: none;
   opacity: 0.75;
   cursor: default;
   pointer-events: none;
   color: var(--btn-primary);
 }
+
+.round-btn {
+  background: var(--sign-in-btn-bg);
+  color: var(--sign-in-btn-color);
+  border: 2px solid var(--sign-in-btn-border);
+  border-radius: 6px;
+  font-size: 0.85rem;
+  font-weight: 600;
+  padding: 0.2rem 0.5rem;
+  margin-right: 0.1rem;
+  cursor: pointer;
+  transition:
+    background 0.18s,
+    color 0.18s;
+}
+.round-btn:hover {
+  background: var(--sign-in-btn-hover-bg);
+  color: var(--sign-in-btn-hover-color);
+}
+
+/* Floating Action Button (FAB) */
+.fab {
+  position: fixed;
+  bottom: 2rem;
+  right: 2rem;
+  background: var(--fab-bg);
+  color: #fff;
+  border: none;
+  border-radius: 50%;
+  width: 56px;
+  height: 56px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
+  cursor: pointer;
+  font-size: 24px;
+  z-index: 1300;
+}
+
+.fab:hover {
+  background: var(--fab-hover-bg);
+}
+
+.fab:active {
+  background: var(--fab-active-bg);
+}