title: bootstrap (4) How to amend custom select arrow to change colour
body: <p>I'm trying to amend the arrow used in Boostraps <code>custom-select</code> css class.  Currently it's black and would prefer to change this to grey, is there an easy way to do this?
  <a href="https://getbootstrap.com/docs/4.0/components/forms/#select-menu" rel="nofollow noreferrer">https://getbootstrap.com/docs/4.0/components/forms/#select-menu</a></p>