v5.6.2

Fixes

• removes display: contents from transparent elements (not what I thought it meant)
• updates docs section on box-shadow hack
• fixes initial text-align value for default browser stylesheets
• removes opinionated backgrounds & borders from form elements; fixes border width & style on universal selector
• fixes initial column-rule width and style for all elements
• updates fallback mixins to match gulp-autoprefixer v4 default settings