Different semantic structures for identically-structured drop-down menus
Being purely CSS-based, these require no javascsript. For some UIs, in order to
pull down the pull-down menus, you need a single tap on the header part.
Option 1: menu as heirarchical ul's
Option 2: menu as non-heirarchical dl's and dd's
Option 3: menu as plain old div's
Option 4: menu as rows in a table