Fix Subscribe/Unsubscribe button style

Author: takezoe

Diff for: src/main/twirl/gitbucket/notifications/issue.scala.html

@@ -8,9 +8,9 @@
   <span class="muted small strong">Notifications</span>
   <div class="pull-right">
     @if(subscribed){
-      <input type="button" class="btn btn-default issue-notification" value="Unsubscribe" data-subscribed="false" />
+      <input type="button" class="btn btn-default btn-sm strong issue-notification" value="Unsubscribe" data-subscribed="false" />
     } else {
-      <input type="button" class="btn btn-default issue-notification" value="Subscribe" data-subscribed="true" />
+      <input type="button" class="btn btn-default btn-sm strong issue-notification" value="Subscribe" data-subscribed="true" />
     }
   </div>
 </div>