Nesting selectors ties the css to your markup. These styles are not reusable components, but one-offs for that particular snippet of html. Look how bad it can g

Nesting selectors ties the css to your markup. These styles are not reusable components, but one-offs for that particular snippet of html. Look how bad it can get: https://github.com/edx/edx-platform/blob/master/lms/static/sass/course/courseware/_sidebar.scss https://github.com/edx/edx-platform/blob/master/lms/static/s... It's basically replicating the html nesting.