Thanks for your help, i fix that issue with
background-color: rgba(0, 0, 0, 0.3)
so it's looks like now
function ol_content_simple(text) {
var cpIsMultiple = /,/.test(o3_cellpad);
var txt = '<table id="mainOverLib" name="mainOverLib" style=" background-color: rgba(0, 0, 0, 0.5)...