Use sprite_icon and variables

app/assets/stylesheets/framework/modal.scss

@@ -6,8 +6,8 @@
     margin-top: 0;
 
     .color-label {
-      font-size: 14px;
-      padding: 6px 10px;
+      font-size: $gl-font-size;
+      padding: $gl-vert-padding $label-padding-modal;
     }
   }
 }

app/assets/stylesheets/framework/variables.scss

@@ -558,6 +558,7 @@ $jq-ui-default-color: #777;
 * Label
 */
 $label-padding: 7px;
+$label-padding-modal: 10px;
 $label-gray-bg: #f8fafc;
 $label-inverse-bg: #333;
 $label-remove-border: rgba(0, 0, 0, .1);

app/views/shared/_label.html.haml

@@ -50,7 +50,7 @@
     - if label.is_a?(ProjectLabel) && label.project.group && can?(current_user, :admin_label, label.project.group)
       = link_to promote_project_label_path(label.project, label), title: "Promote to Group Label", class: 'btn btn-transparent btn-action', data: {confirm: "You are about to promote #{label.title} to a group level. This will make this milestone available to all projects inside #{label.project.group.name}. The existing project label will be merged into the group level. This action cannot be reversed.", toggle: "tooltip"}, method: :post do
         %span.sr-only Promote to Group
-        = icon('level-up')
+        = sprite_icon('level-up')
     - if can?(current_user, :admin_label, label)
       = link_to edit_label_path(label), title: "Edit", class: 'btn btn-transparent btn-action', data: {toggle: "tooltip"} do
         %span.sr-only Edit