Of course all the structural elements for G5 are different so you will need to alter that CSS considerably. In fact, the best thing to do is to create your own by copying one of the existing Gantry 5 block variations. Depending on the template that you use there are already a number of block variations available (usually shown on the "block variations" page of the demo or the "typography" page of the demo). You can use Firefox Inspector or one of the other browser developer tools to find the css styling.
Regards, Mark.
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