fix buttons showing inconsistent styles (#25903)

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

@@ -627,14 +627,6 @@ html {
   }
 }
 
-.button.logo-button {
-  color: $white;
-
-  svg {
-    fill: $white;
-  }
-}
-
 .notification__filter-bar button.active::after,
 .account__section-headline a.active::after {
   border-color: transparent transparent $white;