Design hotfixes and improvements.

frontend/src/components/BottomNav.css

@@ -2,10 +2,6 @@
   display: flex;
   justify-content: space-around;
   align-items: flex-end;
-  position: fixed;
-  left: 50%;
-  transform: translateX(-50%);
-  bottom: 0;
   width: 100%;
   max-width: 48rem;
   z-index: 50;
@@ -14,6 +10,17 @@
   box-shadow: 0 -4px 20px rgba(0, 0, 0, 0.1);
   border-radius: var(--radius-lg) var(--radius-lg) 0 0;
   height: 5.5rem;
+  flex-shrink: 0;
+  margin: 0 auto;
+}
+
+/* Desktop navigation - full width */
+@media (min-width: 1025px) {
+  .bottom-nav {
+    max-width: 100%;
+    padding: 0.25rem 2rem calc(0.5rem + env(safe-area-inset-bottom));
+    border-radius: var(--radius-lg) var(--radius-lg) 0 0;
+  }
 }
 
 .bottom-nav-item {
@@ -57,17 +64,28 @@
   width: 3.5rem;
   height: 3.5rem;
   border-radius: var(--radius-full);
-  background: var(--tertiary-container);
-  color: var(--on-tertiary);
-  box-shadow: 0 4px 14px rgba(70, 0, 173, 0.35);
+  /* Stronger, brighter blue to make scan button easy to find */
+  background: #2b5bb5;
+  color: #ffffff;
+  box-shadow: 0 8px 26px rgba(43, 91, 181, 0.32);
   margin-top: -1.5rem;
-  transition: transform 0.15s;
+  transition: transform 0.12s, box-shadow 160ms ease;
 }
 
 .nav-fab:active {
   transform: scale(0.92);
 }
 
+.nav-fab:hover {
+  transform: translateY(-2px);
+  box-shadow: 0 12px 36px rgba(43, 91, 181, 0.36);
+}
+
+.nav-fab:focus {
+  outline: none;
+  box-shadow: 0 0 0 6px rgba(43,91,181,0.12), 0 8px 26px rgba(43, 91, 181, 0.32);
+}
+
 .nav-badge {
   position: absolute;
   top: 0;
@@ -116,4 +134,4 @@
 
 .nav-elevated.active .nav-label {
   color: var(--tertiary);
-}
+}