Google Chrome - Differences between Mac and PC

I'm developing a website for a customer, and I've tested it with the major browsers on Windows.

Now I'm facing some little differences between Chrome Win and Chrome Mac (same version). These are really minor things, but the customer spotted them, so I'm wonder.. there is some reset I can do via css to make the two version as similar as possible?

I think I've to work with the -webkit prefix of the browser default, do you know any good walkthrough?

I mean: there is some base .css I could use to reset Chrome and to force it to render as similar as possible even cross-platform?

Thanks!

UPDATE: the differences I mention involves mainly font-sizes letterspacing and something related with the height and line-height of the elements.