https://tools.wmflabs.org/replacer/: https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css
Loading from external providers are discouraged. Please see parent tasks and J65.
In your case a direct replacement would be https://tools-static.wmflabs.org/cdnjs/ajax/libs/twitter-bootstrap/3.3.7/css/bootstrap.min.css