This issue is posted on GitHub

/*-- Fix breadcrumb arrow going to the top --*/

/*-- the first icon in breadcrumbs is at the top caused by below --*/

/* http://localhost/media/gantry5/engines/nucleus/css-compiled/joomla.css:206
[class^="icon-"], [class*=" icon-"] {
	margin-right: .25em;
	line-height: 14px;
}
/* http://localhost/media/jui/css/icomoon.css:17
[class^="icon-"], [class*=" icon-"] {
	display: inline-block;
	width: 14px;
	height: 14px;
	*margin-right: .3em;
	line-height: 14px;
}
/* http://localhost/templates/g5_helium/custom/css-compiled/helium_18.css:26
    font-size: 1rem;
    line-height: 2;
}
*/

/* Fix only second identifier might be needed.*/
.breadcrumb [class^="icon-"], .breadcrumb [class*=" icon-"] {
    line-height: 2;
}