I like to use tabs instead of spaces for tabulated lines (INORITE?), but GitHub defaults to 8 space tab width.
Turns out Github honours .editorconfig.
So adding the lines:
[*.{js,jsx,html,sass.scss,handlebars,partial,hbs,json}]
indent_style = tab
indent_size = 4
Will set the size. Also these are useful:
charset = utf-8
trim_trailing_whitespace = true