Remove bulma box-sizing (#411)

* Remove bulma box-sizing

I've been thinking about removing this for awhile. I hadn't been able
to find where it changes anything, but now removing it fixes an issue
with numpy.org.

* Remove more

Author: jarrodmillman

assets/theme-css/bulma.css

@@ -138,14 +138,6 @@ input,
 select {
   margin: 0;
 }
-html {
-  box-sizing: border-box;
-}
-*,
-::after,
-::before {
-  box-sizing: inherit;
-}
 img,
 video {
   height: auto;