.parens {

@var: 1px;
border: (@var * 2) solid black;
margin: (@var * 1) (@var + 2) (4 * 4) 3;
width: (6 * 6);
padding: 2px (6px * 6px);

}

.more-parens {

@var: (2 * 2);
padding: (2 * @var) 4 4 (@var * 1px);
width: (@var * @var) * 6;
height: (7 * 7) + (8 * 8);
margin: 4 * (5 + 5) / 2 - (@var * 2);
//margin: (6 * 6)px;

}

.nested-parens {

width: 2 * (4 * (2 + (1 + 6))) - 1;
height: ((2+3)*(2+3) / (9-4)) + 1;

}

.mixed-units {

margin: 2px 4em 1 5pc;
padding: (2px + 4px) 1em 2px 2;

}