Resolve "BS4: Create new Merge request boxes have different styles"

app/assets/stylesheets/framework/variables.scss

@@ -835,3 +835,5 @@ $font-family-monospace: $monospace-font;
 $input-line-height: 20px;
 $btn-line-height: 20px;
 $table-accent-bg: $gray-light;
+$card-border-color: $border-color;
+$card-cap-bg: $gray-light;

app/views/projects/merge_requests/creations/_new_compare.html.haml

@@ -27,7 +27,7 @@
               = dropdown_filter(_("Search branches"))
               = dropdown_content
               = dropdown_loading
-        .panel-footer
+        .card-footer
           .text-center= icon('spinner spin', class: 'js-source-loading')
           %ul.list-unstyled.mr_source_commit

changelogs/unreleased/48636-new-mr-card-styles.yml

+---
+title: Fix new MR card styles
+merge_request: 20822
+author:
+type: fixed