fix(nav): stop CTA press warp, pin user menu, hide PC hamburger

Lock top-bar button transforms on press; anchor avatar dropdown under
the trigger; show mobile drawer toggle only ≤767 and grid-layout the
mobile header so logo and menu no longer overlap.

assets/css/frontend/nav/zib-mobile-navbar.css

@@ -38,14 +38,16 @@
     margin-top: 5px;
   }
 
+  /* Center layout is grid-driven in nav.css (menu | logo | search).
+   Do NOT absolute-position brand — it overlaps the hamburger. */
   .navbar-top.center .navbar-brand {
-    position: absolute;
-    width: 100%;
+    position: static;
+    width: auto;
     text-align: center;
   }
 
   .navbar-top.center .navbar-brand + .navbar-toggle {
-    float: left;
+    float: none;
   }
 
   .navbar-top.center .navbar-brand > img {

assets/css/frontend/nav/zib-utilities.css

@@ -164,14 +164,31 @@ body.mobile-navbar-show { overflow: hidden; }
 .navbar-top .navbar-collapse > .navbar-right:last-child {
   margin-left: auto;
 }
-.navbar-top .navbar-toggle { display: none; background: none; border: 0; color: inherit; }
+/* Mobile drawer toggle: hidden on PC (nav.css hardens with !important) */
+.navbar-top .navbar-toggle {
+  display: none;
+  background: none;
+  border: 0;
+  color: inherit;
+}
 @media (max-width: 767px) {
-  .navbar-top .navbar-toggle { display: inline-flex; align-items: center; justify-content: center; width: 40px; height: 40px; }
+  .navbar-top .navbar-toggle {
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+    width: 40px;
+    height: 40px;
+  }
   .navbar-top .navbar-collapse,
   .navbar.navbar-top .collapse.navbar-collapse {
     display: none !important;
   }
 }
+@media (min-width: 768px) {
+  .navbar-top .navbar-toggle {
+    display: none !important;
+  }
+}
 
 /* Senior submenu full width under fixed header */
 .navbar-top .sub-menu.senior-submenu {
@@ -348,14 +365,20 @@ body.mobile-navbar-show { overflow: hidden; }
   display: inline-block;
   position: relative;
 }
-/* Sub-user-box width */
+/* Sub-user-box width + anchor under trigger */
 .navbar-top .navbar-right .sub-menu {
   min-width: 280px;
   padding: 0;
+  top: calc(100% + 6px);
+  right: 0;
+  left: auto;
 }
 .navbar-top .navbar-right .sub-menu .sub-user-box {
   min-width: 280px;
 }
+.navbar-top .list-inline > li {
+  position: relative;
+}
 /* Ensure fold trigger visible only mid */
 @media (min-width: 992px) {
   .navbar-top .show-nav-but { display: none !important; }