// (We can't just negate the value with unary minus due to the units.)
$flipSign = function ( $cssValue ) {
// Don't mangle zeroes
// (We can't just negate the value with unary minus due to the units.)
$flipSign = function ( $cssValue ) {
// Don't mangle zeroes
return $cssValue;
} elseif ( $cssValue[0] === '-' ) {
return substr( $cssValue, 1 );
return $cssValue;
} elseif ( $cssValue[0] === '-' ) {
return substr( $cssValue, 1 );