Does not support multiple CSS rules per line

[neonflame4]

css-variables-polyfill/css-var-polyfill.js

Line 66 in c27cb7e

cssVarPoly.varsByBlock[counter] = theCSS.match(/(--.+:.+;)/g) || [];

I suggest changing to something like this:
theCSS.match(/(--[\w-]+:.+);/g)

Otherwise, rules on the same line as the CSS variable are included in the match, and IE 11 throws exceptions. From there, custom variables will not parse.