Fixing the hero widget (#15926)

* Removing last-child padding conflicts with light theme in hero widget

* Add missing background color to widget

* Reset widget.scss to default

* Hope this works

Co-authored-by: koyu <me@koyu.space>

app/javascript/styles/mastodon-light/diff.scss

@@ -707,7 +707,6 @@ html {
   .public-account-bio,
   .hero-widget__text {
     background: $account-background-color;
-    border: 1px solid lighten($ui-base-color, 8%);
   }
 
   .header {