After your tabpanel is rendered you can get access to the panel's tabBar and insert Ext.toolbar.Fill items at the front and back of the tabBar's items. That's how I've done it in the past at least. Don't believe there's a config option for that natively and adding tabs programatically will require that you take the bookending tbfill components into account, but it works.
Nope cant post you css script.
Use firebug or chrome dev tool to inspect the dom element css class and styles and override it with your own.
You can even test it by changing the css value in the debugging tool and see if it does what you want.