Thank you, that is helping me.
I tried all three, and the BBCode is closest to what I want. I learned the NL2BR needs to go after the BBCode in the list, or maybe you can edit it's properties. Easiest to make sure it's after BBCode in the list.
I got the colors and the box with horizontal scrollbar ...

I looked for themes that will do this, but if there are any, I missed them. I want it to show blocks that I denote with <code>text</code> or something similar to show up in a box that is bordered and colored different from the rest of the text. Bonus if the box can be made to only go so wide, and ...