Locate the section for your github remote in the .git/config file. It looks like this:
[remote "origin"]
fetch = +refs/heads/*:refs/remotes/origin/*
url = [email protected]:joyent/node.git
Now add the line fetch = +refs/pull/*/head:refs/remotes/origin/pr/* to this section. Obviously, change the github url to match your project's URL. It ends up looking like this:
tl;dr Developers would like the idea to style components based on a parent's width rather than depend solely on the viewport media query. This would allow modular components to style themselves while being agnostic to the viewport.
There is currently a lot of developer interest in getting a feature like Container Queries (née "Element Queryies") shipped in a browser.
Here are official'ish documents to outline the developer community's desires.