Fix active hover state for navigation section

CHANGELOG.md

@@ -63,6 +63,7 @@
 - Add missing JavaScript exports for `button`, `inPageNavigation`, `inputMask`, `languageSelector`, and `range`. ([#407](https://github.com/18F/identity-design-system/pull/407))
 - Fix `dist/assets/js/main.js` compilation to properly consider browser support. ([#421](https://github.com/18F/identity-design-system/pull/421))
 - Fix strict ES Module import errors due to lack of fully-qualified file path when importing `auto` entrypoint. ([#422](https://github.com/18F/identity-design-system/pull/422))
+- Fix background color when hovering an expanded navigation section on large viewport sizes. ([#418](https://github.com/18F/identity-design-system/pull/418))
 
 ### Internal
 

src/scss/packages/usa-nav/src/_overrides.scss

@@ -42,9 +42,11 @@
     }
   }
 
-  button {
-    &:hover {
-      background-color: color('primary-lightest');
+  @include at-media-max($theme-header-min-width) {
+    button {
+      &:hover {
+        background-color: color('primary-lightest');
+      }
     }
   }
 }