Fixes missing bottom margin for the new button custom metrics

app/views/projects/services/prometheus/_show.html.haml

@@ -22,7 +22,7 @@
             = icon('spinner spin', class: 'metrics-load-spinner')
             = s_('PrometheusService|Finding custom metrics...')
         .empty-metrics.hidden.js-empty-custom-metrics
-          = link_to s_('PrometheusService|New metric'), new_project_prometheus_metric_path(@project), class: 'btn btn-success prepend-top-10 prepend-left-10'
+          = link_to s_('PrometheusService|New metric'), new_project_prometheus_metric_path(@project), class: 'btn btn-success prepend-top-10 prepend-left-10 append-bottom-10'
         %ul.list-unstyled.metrics-list.hidden.js-custom-metrics-list
 
     .panel.panel-default.js-panel-monitored-metrics{ data: { active_metrics: active_common_project_prometheus_metrics_path(@project, :json), metrics_help_path: help_page_path('user/project/integrations/prometheus_library/metrics') } }