when you need to calculate measurements in vw, you need a context (starting point to define what will be 1vw) after that you pass the amount in pixels you want to convert to vws.

get-vw-mixin.scss

$context:960;// size you want to start calculating
@function get-vw($target) {
	$vw-context: ($context * .01) * 1px;
	@return ($target/$vw-context) * 1vw;
}
//usage

.page-obituary{
	h1{
		color: #2b6295;
		font-size: rem-calc(30);
		line-height: 1;
		margin-bottom: 0;

		@include breakpoint(800){
			font-size: get-vw(30px);
		}
  }