Sass negative variable value?

Question

I have a couple of scss selectors where I use the same amount positive and negative, as in:

padding: 0 15px 15px;
margin: 0 -15px 20px -15px;

I'd prefer to use a variable for all the 15px amounts, but this does not work:

$pad: 15px;
padding: 0 $pad $pad;
margin: 0 -$pad 20px -$pad;

The margin amounts convert to positive numbers. Am I missing something?

Answer 1

Try it like this

margin: 0 (-$pad) 20px (-$pad);

Answer 2

A more sane solution according to sass guidelines would be to interpolate variables like the following example:

margin: 0 -#{$pad} 20px -#{$pad};

An example: https://www.sassmeister.com/gist/c9c0208ada0eb1fdd63ae47830917293