The theming firehose (NB for designers & front-end developers new to Drupal)

You theme with the mark-up you have, not the mark-up you’d like to have. That’s the essential truth that designers and front-end developers new to Drupal need to understand. You don’t get to construct your pages from scratch, building out essentials, never a wasted div, never an extraneous class. No, you have to flip the entire process around. With Drupal you’re getting markup shot at you from a firehose, and as a themer you need to sop it all up and make it pretty....

 · Laura Lis Scott