Looks like a CSS error. For others to resolve this just edit the following : 

wp-content/plugins/wpforo/wpf-themes/classic/style.css

Find this line : 

#wpforo #wpforo-wrap .wpforo-post .wpf-right .wpforo-post-content{padding:10px 30px 10px 10px; min-height:130px; font-size:14px; line-height:18px; Word-wrap: break-word;}

And add the orange... For future releases might be a good idea to include this 🙂