Board Thread:Support Requests - Getting Technical/@comment-24527343-20171024063359

What CSS code is required to change the color of an infobox header, background color, and how to add and change the color of a border for the infobox? This might be relevant. (F3-search the keyword "mari").

I am also trying to figure out the problem with this. No matter what I try, it still shows the same "There is a problem with parsing the infobox, Opening and ending tag mismatch, Premature end of tag" message. 