Specificity is not only the aspect of CSS that will make any fluent presentation stop in its tracks (or am I the only one who has problems pronouncing it?), it is also a very important part of CSS design. Basically it allows to override settings defined earlier in a stylesheet by adding other element, class or ID names.
will not apply any longer when you add another id of an element the h1 resides in:
While it is easy to trial and error initially, the more you mix and match elements, IDs and classes the harder it can get to predict the outcome.
Andy couldn’t stop his nerdy alter ego and came up with a star wars based, wonderful cheatsheet on the subject which initially had some errors that Molly rectified.
Wonderful stuff and something to hang up in the office.