Just for the case that someone will solve the same problem in future: the solution is to use something like
ADD_CSS_FILE("left.css");
and define custom file left.css.
WeBWorK Main Forum
Left align preview of essay answers - is it possible?
This forum has a limit to the number of forum postings you can make in a given time period - this is currently set at 10 posting(s) in 1 day