Contributing

Coding guide lines

Make sure your code follows the PSR-12 code style and is .editorconfig valid. You may use composer run phpcs and Editorconfig-Checker to verify that.
Use use statements wherever possible instead of writing the fully qualified name.
Order the composer/npm dependencies alphabetically.
Do not use code from the includes directory anywhere else.
Please cover your code by unit tests. Code under includes does not require tests.
Do not use vendor prefixes like -webkit in styles. This is done by PostCSS + Autoprefixer according to the .browserslistrc.

Please create single pull requests for every feature instead of creating one big monster of pull request containing a complete rewrite.