Litestrap is extremely lightweight version of Bootstrap CSS Framework
Bootstrap is very good, except cases when you need to embed to your website something not heavy and quickly downloadable by browser. Really, the most of the times you need only the structure (scaffolding) from wide Bootstrap's features list.
For this we have done our own compilation of Bootstrap and called it Litestrap.
This website is built with using Litestrap. As you can see all adaptive markup features are working fine.
Its very short list of really needed features:
In two words - anything else. You can be sure that it does not includes: