It’s unlikely your code has this boogeyman. However, if your front-end code is from 2005, you might want to check under the bed for it. I’m not going to explain why it should not be used because I don’t even remember.
A redirect might make a URL such as http://treefrogs.com into http://www.treefrogs.com or http://treefrogs.com/ (simply adding the forward slash). Redirects slow down web sites, so remove any redirects that are not required.
IDs must be unique to an HTML document.
We recommend that CSS files larger than 5K have whitespace removed. Search “minify CSS.”