Add a 'uniform' icon style

client/scss/components/_icons.scss

@@ -164,4 +164,9 @@ svg.icon-spinner { // TODO: leave only class when iconfont styles are removed
     &.default {
         @include svg-icon(1.5em);
     }
+
+    &.uniform {
+        width: 1em;
+        height: 1em;
+    }
 }

wagtail/admin/templates/wagtailadmin/shared/workflow_status.html

@@ -26,9 +26,9 @@
         {% for task in workflow_tasks %}
             <span data-wagtail-tooltip="{{ task.name }}: {{ task.status_display }}">
                 {% if task.status == 'approved' %}
-                    {% icon "success" title=approved_title %}
+                    {% icon "success" title=approved_title class_name="icon uniform" %}
                 {% else %}
-                    {% icon "radio-empty" title=incomplete_title %}
+                    {% icon "radio-empty" title=incomplete_title class_name="icon uniform" %}
                 {% endif %}
             </span>
         {% endfor %}