1) add styles and scripts in your document.
suffer your markup, as where the styles intersect and obviously will have to override
2) loading of items on buttrape in an iframe
the styles have to spit, however, this solution is quite a lot of shortcomings in terms of content and control it all - you need to understand the specifics.
3) do as in P1, but! be used to bootstrap prefix styles that will allow you to dissociate THEIR identity from vashih styles, see here