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...