add an indeterminate progress bar

[jtwaleson]

I'm using concrete.css for a mini project (thanks!) but needed an indeterminate progress bar.

This code adds it.

I copied some parts of the implementation from pico.css and stripped it down to a bare minimum. It supports not showing the animation for browsers that prefer reduced motion.

Tested on Chrome & Firefox on Linux.

[louismerlin]

Hello Jouke! Thank you very much for the PR, I super appreciate it.

I don’t know that I see concrete as having an animated element. I won’t be super online these next few days but I’ll iterate on your PR as soon as I’m able 😄

Or feel free to do it if you have an idea!

[jtwaleson]

Hello Jouke! Thank you very much for the PR, I super appreciate it.

I don’t know that I see concrete as having an animated element. I won’t be super online these next few days but I’ll iterate on your PR as soon as I’m able 😄

Or feel free to do it if you have an idea!

As having an animated "indeterminate" state is natively supported by HTML I'd argue that it fits the spirit of concrete.css. I'm using my fork right now and in my application it "feels" very natural. Much better than the spinner I was using before. That'd be my reasoning but of course it's your call!

Please let me know if there are improvements you'd like to see in the PR and I'll give it my best :)