FB fixed

src/client/styles/scss/theme/_override-agileadmin.scss

@@ -112,6 +112,8 @@ a {
     }
   }
   &.alert-danger {
+    $danger: #ff0a54 !default;
+    background: $danger;
     a:not(.btn) {
       &:hover,
       &:focus {

src/server/views/widget/alert_siteurl_undefined.html

@@ -1,5 +1,5 @@
 {% if !getConfig('crowi', 'app:siteUrl') %}
-<div class="myadmin-alert bg-danger text-white mb-0 px-4 py-2">
+<div class="myadmin-alert alert alert-danger text-white mb-0 px-4 py-2">
   <i class="icon-exclamation"></i>
   {{ t("security_setting.alert_siteUrl_is_not_set", '<a href="/admin/app">' + t('App settings') + '<i class="icon-login"></i></a>') }}
 </div>