* refactor: Convert pixelated borders from box-shadows to border-images
Our previous usage of `box-shadows` and pseudo elements proved to be pretty buggy. Converting to
`border-image`s seems to have fixed a lot of the issues that `box-shadows` caused, such as
`background-color`s appering over top of our borders.
BREAKING CHANGE: This change both eliminates pseudo elements from several components, and adds
pseudo elements to components that did not have them before. This could cause compatibility issues
for users that relied on the existence of those pseudo elements for various styling techniques.
* style(buttons): Remove superfluous commented code
Previously, we were using the `color` property to determine the color of the border around `<dialog
/>` elements. The issue with this is that it requires the text color to match the border color. I've
fixed this by moving the border color declarations into the `box-shadow` property.
The dialog styles added by @sophi-est weren't being loaded into the compiled stylesheet. I've added
them to the elements index file and moved the rounded corners styles into and `.is-rounded` modifier
class.
