Apply new GitLab UI for buttons in empty issue placeholder

app/views/projects/issues/import_csv/_button.html.haml

@@ -2,7 +2,7 @@
 - can_edit = can?(current_user, :admin_project, @project)
 
 .dropdown.btn-group
-  %button.btn.gl-button.rounded-right.text-center{ class: ('has-tooltip' if type == :icon), title: (_('Import issues') if type == :icon),
+  %button.btn.gl-button.btn-default.rounded-right.text-center{ class: ('has-tooltip' if type == :icon), title: (_('Import issues') if type == :icon),
     data: { toggle: 'dropdown', qa_selector: 'import_issues_button' }, 'aria-label' => _('Import issues'), 'aria-haspopup' => 'true', 'aria-expanded' => 'false' }
     - if type == :icon
       = sprite_icon('import')

app/views/shared/empty_states/_issues.html.haml

@@ -42,7 +42,7 @@
             - if project_select_button
               = render 'shared/new_project_item_select', path: 'issues/new', label: _('New issue'), type: :issues, with_feature_enabled: 'issues'
             - else
-              = link_to _('New issue'), button_path, class: 'btn btn-success', id: 'new_issue_link'
+              = link_to _('New issue'), button_path, class: 'btn gl-button btn-success', id: 'new_issue_link'
 
             - if show_import_button
               = render 'projects/issues/import_csv/button', type: :text

changelogs/unreleased/gl-button-empty-issue-placeholder.yml

+---
+title: Apply new GitLab UI for buttons in empty issue placeholder
+merge_request: 53554
+author: Yogi (@yo)
+type: other