diff --git a/lib/rxp-hpp.js b/lib/rxp-hpp.js
index f401b88..69ed933 100644
--- a/lib/rxp-hpp.js
+++ b/lib/rxp-hpp.js
@@ -665,8 +665,14 @@ var RealexHpp = (function () {
 			// check for iframe resize values
 			if (evtdata.iframe) {
 				if (!isMobileNewTab()) {
-					var iframeWidth = evtdata.iframe.width;
-					var iframeHeight = evtdata.iframe.height;
+					// get iframe width as int
+					var iframeWidth = parseInt(evtdata.iframe.width.replace("px", ""), 10);
+					// get iframe height as int
+					var iframeHeight = parseInt(evtdata.iframe.height.replace("px", ""), 10);
+					// calculate half of iframe width to reuse it
+					let halfWidth = iframeWidth / 2;
+					// get iframe top coord
+					let iframeTop = parseInt(iFrame.style.top.replace('px', ''), 10);
 
 					var iFrame;
 					var resized = false;
@@ -680,9 +686,12 @@ var RealexHpp = (function () {
 						e.instance.events.onResize(evtdata.iframe);
 					}
 
-					if (iframeWidth === "390px" && iframeHeight === "440px") {
-						iFrame.setAttribute("width", iframeWidth);
-						iFrame.setAttribute("height", iframeHeight);
+					// if iframe size has changed
+					if (iFrame.getAttribute('width') !== iframeWidth + 'px' || iFrame.getAttribute('height') !== iframeHeight) {
+						// calculate maxHeight so that iframe has equal margin at top and bottom if its height exceeds calculated maxHeight -> no need to scroll browser window but light box
+						let maxHeight = window.innerHeight - (2 * iframeTop);
+						iFrame.setAttribute("width", iframeWidth + 'px'););
+						iFrame.setAttribute("height", Math.min(iframeHeight, maxHeight) + 'px');
 						resized = true;
 					}
 
@@ -700,16 +709,24 @@ var RealexHpp = (function () {
 							overlay.style.overflowY = "scroll";
 						}
 					} else if (!e.embedded && resized) {
-						iFrame.style.marginLeft = (parseInt(iframeWidth.replace("px", ""), 10) / 2 * -1) + "px";
+						// center iframe horizontally
+						iFrame.style.marginLeft = -1 * halfWidth + 'px';
+						// set maxHeight style to be the same as calculated above
+						iFrame.style.maxHeight = `calc(100% - ${2 * iframeTop}px)`;
 					}
 
 					if (!e.embedded && resized) {
 						// wrap the below in a setTimeout to prevent a timing issue on a
 						// cache-miss load
-						setTimeout(function () {
-							var closeButton = document.getElementById("rxp-frame-close-" + randomId);
-							closeButton.style.marginLeft = ((parseInt(iframeWidth.replace("px", ""), 10) / 2) -7) + "px";
-						}, 200);
+						const closeButton = document.getElementById("rxp-frame-close-" + randomId);
+						if (closeButton) {
+							// set margin immediately if closeButton is present
+							closeButton.style.marginLeft = halfWidth - closeButton.width / 2 + 'px';
+						} else {
+							setTimeout(function () {
+								closeButton.style.marginLeft = halfWidth - closeButton.width / 2 + 'px';
+							}, 200);
+						}
 					}
 				}
 			} else {
@@ -1012,4 +1029,4 @@ var RealexHpp = (function () {
 		_internal: internal
 	};
 
-}());
\ No newline at end of file
+}());