Looks very good! Could you additionally factor out the style of grid into all.css and use that style instead of inlined one? We'll be able to reuse it later on in other grids.

Inline styles added to all.css

Well.. first of all I would name the class 'simple_grid' so that we really can reuse it on other pages.
Then, your way of importing styles looks a bit strange, we need to add 'all.css' file in zk.xml so that it is imported automatically at every page, then we should refer to the style by name: style="simple_grid".