What is the best coding practice for CSS to a website?
For developers using a CSS preprocessor, the best practice is to write @extend rules first and @include rules second. The reason for that is the fact that you're aware right away that those styles are inserted into the selector, and you are able to easily override them below it.
How do I make links stay active when clicked?
A link becomes active when you click on it. Tip: The :active selector can be used on all elements, not only links. Tip: Use the :link selector to style links to unvisited pages, the :visited selector to style links to visited pages, and the :hover selector to style links when you mouse over them.