cleanup package.json, update sass, fix router (css class issue)

src/nav/menu.scss

@@ -1,16 +1,16 @@
-@import "./nav";
+@use "./nav";
 
 .menu {
   position: absolute;
   display: flex;
   flex-direction: column;
-  background: $menu;
+  background: nav.$menu;
   z-index: 10;
   color: white;
   width: 25%;
   height: 100vh;
 
   div {
-    padding: $padding;
+    padding: nav.$padding;
   }
 }