Bringing calculator aesthetic inline with MAS standards

* Removes the grey container
* Using standard (budget planner) style sliders
* Using new form styles
* Removing callout background colour override, using whatever dough supplies

**Note: this makes the calculators track the `master` branch of dough, and therefore receive updates automatically.**

Once merged, the form styling will be promoted to `dough` (which will properly handle error states and componentise the CSS).