Update _ads.scss

src/assets/scss/_ads.scss

@@ -9,6 +9,7 @@
   display: block;
   max-width: 400px;
   padding: 15px 15px 15px 160px;
+  // Custom blog property
   // `auto` is some extra code compared to the upstream rule
   // to center horizontally the ads at small breakpoints
   margin: 2rem auto 0;