Background colors and borders can be added using the \bbox{} macro. For example \bbox[#FD9,border:2px solid purple,10px]{ \bbox[red]{r} + \bbox[green,5px]{\color{yellow}{g}} + \bbox[border:2px dashed blue,3px]{b} } produces \[ \bbox[#FD9,border:2px solid purple,10px]{ \bbox[red]{r} + \bbox[green,5px]{\color{yellow}{g}} + \bbox[border:2px dashed blue,3px]{b} } \] Background color, padding amount, and border specifications can be in any order.