Change onboarding prompt to follow suggestions carousel in web UI (#28878)

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

@@ -578,3 +578,16 @@ html {
 .poll__option input[type='text'] {
   background: darken($ui-base-color, 10%);
 }
+
+.inline-follow-suggestions {
+  background-color: rgba($ui-highlight-color, 0.1);
+  border-bottom-color: rgba($ui-highlight-color, 0.3);
+}
+
+.inline-follow-suggestions__body__scrollable__card {
+  background: $white;
+}
+
+.inline-follow-suggestions__body__scroll-button__icon {
+  color: $white;
+}