box-sizing: inherit

[franciscop-invast]

The box-sizing: border-box; fix is one of the first normalizing techniques I use when starting from scratch. But since I discovered the improvement by CSS-Tricks and Paul Irish improved the original post, this is the best modern recommendation:

/* apply a natural box layout model to all elements, but allowing components to change */
html {
  box-sizing: border-box;
}
*, *:before, *:after {
  box-sizing: inherit;
}

So, my suggestion here is to update the style to follow that. I can do a PR if needed.

[franciscop-invast]

I see in the code it's fixed, should the documentation be updated then to reflect it?

Sets box-sizing: border-box;

To:

Sets box-sizing: inherit;

[sindresorhus]

There's nothing to change. box-sizing: border-box refers to what it changes for the whole document. The inherit part is just an implementation detail.