How to add an array of classes to a div?

[PlusDalaDrereblackjack]

I have a website and I should make certain divs transparent. I don't want to duplicate my divs with a transparent tag. I want to archieve something like this.\[code\].wrapper { --div properties-- }.transparent { --transparency properties --}\[/code\]I want to set class attributes like this.\[code\]<div class="wrapper . transparent"></div>\[/code\]So this div would get all the properties from wrapper style, then apply a transparent background.