themes/vanilla/assets/scss/sidenotes.scss

@@ -13,7 +13,9 @@ $sidenote-highlight-border-width: .2rem;
         }
 
         .sidenote-content {
-            border: $standard-border-width dashed;
+            border: $sidenote-highlight-border-width dashed;
+            padding: $sidenote-padding -
+                ($sidenote-highlight-border-width - $standard-border-width);
             border-color: $primary-color;
         }
     }

themes/vanilla/assets/scss/style.scss

@@ -18,12 +18,9 @@ $standard-border: $standard-border-width solid $border-color;
     border-radius: .2rem;
 }
 
-html {
-  font-size: 0.152778in;
-}
-
 body {
   font-family: $font-body;
+  font-size: 1.0rem;
   line-height: 1.5;
   margin-bottom: 1rem;
   text-align: justify;