I would say an ability to develop a UI while following a shop's preferred style guideline. I would say a mastery of CSS3+HTML is necessary, advanced JS related

I would say an ability to develop a UI while following a shop's preferred style guideline. I would say a mastery of CSS3+HTML is necessary, advanced JS related to DOM manipulation is also welcome. Familiarity with CSS preprocessors would be considered big +. A taste for good design as well ?