add rgba

src/client/styles/scss/theme/_apply-colors.scss

@@ -294,6 +294,12 @@ pre:not(.hljs):not(.CodeMirror-line) {
       color: $secondary;
     }
   }
+
+  .nav-link {
+    &:hover {
+      background-color: rgba(orange, 0.25);
+    }
+  }
   .nav-link svg {
     fill: $color-link;
   }