Höhe des Iframes wird nun durch Flex-Box bestimmt

resources/assets/css/style.css

+body {
+	display: -webkit-box;      /* OLD - iOS 6-, Safari 3.1-6 */
+	display: -moz-box;         /* OLD - Firefox 19- (buggy but mostly works) */
+	display: -ms-flexbox;      /* TWEENER - IE 10 */
+	display: -webkit-flex;     /* NEW - Chrome */
+	display: flex;             /* NEW, Spec - Opera 12.1, Firefox 20+ */
+	-webkit-flex-direction: column;
+	flex-direction: column;
+	height: 100%;
+}
 nav {
 	border-bottom: 5px solid rgb(255,128,0);
 	height:48px;
@@ -42,6 +52,8 @@ nav>.main>#proxy-text>a.btn{
 	border: 0;
 	width: 100%;
 	height: calc(100% - 53px);
+	-webkit-flex-grow: 1;
+	flex-grow: 1;
 }
 
 .content-container {