How do i overide the default css styling in my template by designing a new template? Example template is called sponsor and the css is sponsor.css and not k2.css.

Hi. Please take a look at getk2.org/documentation/tutorials/item/174-templating-with-k2-and-the-concepts-of-sub-templates

You can also take a look at css4k2 which will allow you to have a separate css for each override