Banner chevron style conflict

[DaveSkender]

The USWDS banner component chevron is not rendering correctly.

I can't entirely explain the root cause, but suspect it has something to do with the Jekyll compilation of CSS. There appears to be a conflict happening with .usa-banner__button::after in USWDS v2.12.x.

I've been able to resolve this problem with a workaround by adding mini_racer and jekyll-autoprefixer:

# GemFile
ruby '>= 2.7.4'

source "https://rubygems.org"

gem "jekyll", "~> 3.9"
gem "mini_racer" # --> added
gem "sprockets", "~> 3.7"
gem "kramdown-parser-gfm", "~> 1.1.0"

group :jekyll_plugins do
  gem "jekyll-feed", "~> 0.15"
  gem 'jekyll-redirect-from'
  gem 'jekyll-paginate-v2', "3.0.0"  
  gem 'jekyll-sitemap'
  gem 'jekyll-seo-tag'
  gem 'jekyll-autoprefixer'  # --> added
  gem "jekyll-assets", "~> 3.0", group: :jekyll_plugins
end

...

• ⚠️ There are known issues with mini_racer that can be problematic - see https://github.com/rubyjs/mini_racer/issues/220