Expected:
Parallax translation to work in IE11

Actual:
No transform style is set to bound elements in IE11. Tested in Browserstack.

Cause:
IE11 defaults marginTop to auto, so parseInt(n.marginTop) return NaN

Short term fix:
Explicitly set margin-top styles to a number value on any elements using the directive to get a proper calculation.

See:
https://github.com/jsnanigans/vue-parallax-js/blob/master/src/vue-parallax-js.js#L64
and
https://github.com/jsnanigans/vue-parallax-js/blob/master/src/vue-parallax-js.js#L81