:art: sticky top menu for nav

vue-theme/src/app.vue

         nav, footer
             &.main
                 background-color: pink
-                padding: 0 $ms
                 width: 100%
                 ul > li
                     padding: 0 $ms

vue-theme/src/components/navigation/navigation.vue

 @import '../../sss/variables.sss'
 
 nav.main
+    position: sticky
+    top: 0
     background-color: lightblue
     a > h1
         margin: 0