SCSS underline behind descender mixin

@mixin underline($start, $end, $borderThickness) {
	/* This linear gradient background image creates a stripe behind the area under the letter allowing the descenders of the text to go on top */
	background-image: linear-gradient(180deg, $color-brand-background 0%, $color-brand-background $start, #9ecc3b $start + 1, #9ecc3b $end, $color-brand-background $end + 1);
	border-bottom: $borderThickness $color-brand-primary solid;
	line-height: 1.3em;
	text-shadow: 1px 1px 1px $color-brand-background;
}