Improve mobile responsiveness across pages

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

frontend/src/components/Header.module.css

@@ -1,12 +1,15 @@
 .header {
+  width: min(100% - 2rem, 1220px);
   max-width: 1220px;
   margin: 1rem auto;
 }
 
 .nav {
   display: flex;
-  height: 5rem;
+  min-height: 5rem;
   align-items: center;
+  flex-wrap: wrap;
+  gap: 0.5rem 1rem;
   text-transform: uppercase;
 }
 
@@ -41,6 +44,8 @@
 .navItems {
   display: flex;
   align-items: center;
+  flex: 1;
+  flex-wrap: wrap;
   padding: 0;
   margin: 0;
   list-style: none;
@@ -58,6 +63,32 @@
   color: white;
 }
 
+@media (max-width: 640px) {
+  .nav {
+    align-items: flex-start;
+  }
+
+  .logoNav {
+    margin: 0 auto;
+  }
+
+  .navItems {
+    justify-content: center;
+    gap: 0.25rem;
+  }
+
+  .navLink {
+    display: inline-block;
+    padding: 0.5rem;
+    font-size: 0.8rem;
+  }
+
+  .brand {
+    padding-left: 0;
+    font-size: 2.5rem;
+  }
+}
+
 /* FIXME: Duplicates Splash styles */
 .brand {
   padding-left: 1rem;