Instead of this:
... have this:
Add code below to EXTRA.css template:
.bbCodeBlock pre {
line-height: 26px !important;
padding: 0 10px 0 10px !important;
background-image: -webkit-repeating-linear-gradient(top, rgba(0,0,0,.015) 0px, rgba(0,0,0,.015) 26px, rgba(0,0,0,.045) 26px...