While that's cool, it's not quite what the OP achieves. Using this mixin will turn whatever you apply it to into a solid-color triangle with the passed-in options. The triangle will need to be its own element.
OP adds two triangles to whatever it is applied to, one for the border color, another to cover it up with the background color. And it doesn't require any additional elements... it just adds these to whatever you are applying it to.
You're totally right. I have a mixin that makes a bubble like that too, but it's built from a few different mixins that each build on each other and I didn't want to post a buttload of code in a comment. You can see an example of how mine looks if you hit this page (http://roots.carrotbeta.com/docs/) and scroll down to the UI section
thanks! it's closed and not yet public right now because the docs aren't finished yet - but this is how they look. I plan to have every section be live customizable and reflect implementation with a live code example to the left as is the case with the typography section. once the docs are done I'm planning on open sourcing it. If you want to use it and/or test it out, hit me on twitter @jescalan
OP adds two triangles to whatever it is applied to, one for the border color, another to cover it up with the background color. And it doesn't require any additional elements... it just adds these to whatever you are applying it to.