Menu Tabs Wrap

Hi,
I am updating some older ASPRunner websites from version 5.0
One of the sites has about 12 tabs for the menus and used to wrap around depending on the size of the screen. Whilst this wasn't always the prettiest option it does the job.
Unfortunately with version 5.1 build 327 the tabs do not wrap and the window always fits to 100% of the unwrapped tabs which makes this extend about 150% of the screen width at best.
Please can you advise how to make the tabs wrap...
Kind regards.