diff --git a/app/views/shared/settings/show.html.haml b/app/views/shared/settings/show.html.haml
index d591c9a..b307ec0 100644
--- a/app/views/shared/settings/show.html.haml
+++ b/app/views/shared/settings/show.html.haml
@@ -1,6 +1,7 @@
 - page_title t("fluentd.settings.#{target_plugin_name}.show.page_title")
 
-.well
-  = raw t("fluentd.settings.#{target_plugin_name}.option_guide")
+.card
+  .card-body.bg-light
+    = raw t("fluentd.settings.#{target_plugin_name}.option_guide")
 
 = render "shared/settings/form"