Box-sizing on Blackberry

[ColeCraft]

I'm almost done with a project and now I'm facing a problem I don't know how to solve.I did the whole css styling with the box-sizing: border-box (with ie6/7 polyfill) applied and it worked like a charme on every device I tested, until I picked up a blackberry. It doesn't support box-sizing (actually it does, but only from the very last version) and now all my layout is broken. Since the project is almost finished I don't want to go back and update every single stylesheet to not use that css rule. What do you think would be the best way to tackle this?speaking about this:http://caniuse.com/#search=box-sizingThank you