This little plugin adds a new section to the Customizer which allows you to add CSS at different breakpoints without having to manually write media queries.
It creates the following custom CSS fields:
- All screen sizes
- Mobile only
- Desktop only
You can also change the breakpoint at which the mobile and desktop media queries change.
Yes, at some stage it will.
By default, WordPress' Additional CSS is output as an inline style in the <head> section of your site. This isn't great as it can't be cached. Instead of doing that, this plugin uses dynamic CSS which is treated just like a CSS file.
Probably, create a new issue here and I'll consider adding your feature request.