Sass-Mixin-VW-Font-Size via https://github.com/forepoint/Sass-Mixin-VW-Font-Size/blob/master/_vw-font-size.scss

_vw-font-size.scss

/*------------------------------------*\
    $VW FONT SIZE
\*------------------------------------*/

/**
 * 
 * Used to create a vw font-size value based of a px value passed through to the mixin.
 * Works alongside the mq() mixin and the strip-unit() function from our Sass Package
 *
 * This is an experimental Mixin, Do not use in a production environment.
 *
 * Usage: @include vw-font-size(( size:16,breakpoints:$mq-breakpoints, line-height: 24 ));
 *
 * @author Adam Bulmer
 * @author Tim Perry
 * @version 0.1a
 * 
 */
@mixin vw-font-size( $args ) {

    $breakpoints: map-get( $args, breakpoints );

    $font-size: map-get( $args, size );
    $font-size: 16 !default;
    
    $line-height: map-get( $args, line-height );
    $line-height: 24 !default;

    @each $name, $value in $breakpoints {
        @include mq( $from:$name ) {
            @include mq( $to:large ) {
                
                font-size: $font-size+px;
                font-size: ( strip-unit( $font-size ) / strip-unit( $value ) ) * 100+vw;

                line-height: $line-height+px;
                line-height: ( strip-unit( $line-height ) / strip-unit( $value ) ) * 100+vw;
            
            }
        }
    }

}