Simple bootstrap mobile files for mock up?

I'm building a mock up of a mobile site. I made a drop down accordion mobile menu in Muse and now they want the "fly in from the left" off-canvas style menu. I don't want to have to spend $$ on this by buying a third-party Muse widget as it's just a mock up. Are there any files or templates out there that will allow me to edit to make the mock up in BS and/or CSS?

Thanks.