Upstream: https://github.com/SnowdogApps/magento2-theme-blank-sass
Plus following changes:
- Remove usage of
lib-vendor-prefix - Remove usage of
lib-css - Changes some false values to null, to benefit from Sass behaviour of skipping the properties which have null values
- Add styles for ReCaptcha module
- Removes some files that are unneccessary (JS, fonts, some config, etc.)