Implement css variables

[BriceShatzer]

If I'm not going to use preprocessing or whatever than I should at a minimum us css variables to share colors, padding, etc. across the file.

Not supported by IE so...

• Use this polyfill (CDN link)
• with this targeting:

const isIE10orLess = window.navigator.msPointerEnabled;
const isIE11 = '-ms-scroll-limit' in document.documentElement.style && '-ms-ime-align' in document.documentElement.style;
if (isIE10orLess || isIE11) {doPolyFill()}