Here is some code that I a short while ago wrote. I think that it offers a simple explanation of combining class/ID names with pseudoclasses. These are typically all identified in CSS as at-rules. They are Distinctive Recommendations for your browser, circuitously connected to styling of (X)HTML/XML things in Web https://social-lyft.com/story9201909/helping-the-others-realize-the-advantages-of-selected-left-right-column