diff --git a/welco/templates/welco/home.html b/welco/templates/welco/home.html
index ab43f65..7c90c51 100644
--- a/welco/templates/welco/home.html
+++ b/welco/templates/welco/home.html
@@ -37,7 +37,8 @@ $('div.cell').delegate('h2', 'click', function() {
 $(window).on('resize', function() {
 	if ($('.top iframe').length == 1) {
 		var top_form_height = $('.top form').height();
-		$('.top iframe').css('height', 'calc(100% - ' + top_form_height + 'px)');
+		var top_height = $('.top > div').height();
+		$('.top iframe').css('height', top_height - top_form_height);
 	} else {
 		$('iframe').css('height', '100%');
 	}