diff --git a/package.json b/package.json
index 2da86cdb..b114a2b9 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "processout.js",
-  "version": "1.0.5",
+  "version": "1.0.6",
   "description": "ProcessOut.js is a JavaScript library for ProcessOut's payment processing API.",
   "scripts": {
     "build:processout": "tsc -p src/processout && uglifyjs --compress --keep-fnames --ie8 dist/processout.js -o dist/processout.js",
diff --git a/src/processout/actionhandler.ts b/src/processout/actionhandler.ts
index 62ac9eeb..96ba7ad8 100644
--- a/src/processout/actionhandler.ts
+++ b/src/processout/actionhandler.ts
@@ -61,8 +61,8 @@ module ProcessOut {
     }
 
     export type IframeOverride = {
-        width: number,
-        height: number
+        width: number | string,
+        height: number | string,
     }
 
     export class ActionHandlerOptions {
@@ -74,8 +74,8 @@ module ProcessOut {
         public newWindowWidth?: number;
 
         // Specifies how big the iframe is, it can be overridden by IframeOverride
-        public iframeWidth: number = 440;
-        public iframeHeight: number = 480;
+        public iframeWidth: number | string = 440;
+        public iframeHeight: number | string = 480;
 
         // gatewayLogo is shown when the action is done on another tab or window
         public gatewayLogo?: string;
@@ -144,8 +144,14 @@ module ProcessOut {
 
             if(override) {
                 this.flow = ActionFlow.IFrame;
-                this.iframeWidth = override.width;
-                this.iframeHeight = override.height;
+
+                if (override.width) {
+                    this.iframeWidth = override.width;
+                }
+
+                if (override.height) {
+                    this.iframeHeight = override.height;
+                }
             }
         }
     }
@@ -228,9 +234,15 @@ module ProcessOut {
                 iframeWrapper.style.width = "100%";
                 iframeWrapper.setAttribute("style", "position: fixed; top: 0; left: 0; background: rgba(0, 0, 0, 0.5); z-index: 9999999; overflow: auto;");
 
+                // If the option is number it means that we should use pixels here for the sake of 
+                // backward compatibility. If not - then we use it as value since user can pass
+                // any unit like percentages e.g. 100%, calc(100% - 80px), 30rem etc
+                const width = typeof this.options.iframeWidth === 'number' ? `${this.options.iframeWidth}px` : this.options.iframeWidth
+                const height = typeof this.options.iframeHeight === 'number' ? `${this.options.iframeHeight}px` : this.options.iframeHeight;
+
                 // Create the iframe to be used later
                 var iframe = document.createElement("iframe");
-                iframe.setAttribute("style", `margin: 1em auto; width: ${this.options.iframeWidth}px; height: ${this.options.iframeHeight}px; max-width: 100%; max-height: 100%; display: block; box-shadow: 0 15px 35px rgba(50, 50, 93, 0.1), 0 5px 15px rgba(0, 0, 0, 0.07); background-color: #ECEFF1; background-image: url("${this.instance.endpoint("js", "/images/loader.gif")}"); background-repeat: no-repeat; background-position: center;")`);
+                iframe.setAttribute("style", `margin: 1em auto; width: ${width}; height: ${height}; max-width: 100%; max-height: 100%; display: block; box-shadow: 0 15px 35px rgba(50, 50, 93, 0.1), 0 5px 15px rgba(0, 0, 0, 0.07); background-color: #ECEFF1; background-image: url("${this.instance.endpoint("js", "/images/loader.gif")}"); background-repeat: no-repeat; background-position: center;")`);
                 iframe.setAttribute("frameborder", "0");
                 iframe.onload = function() {
                     // Remove the background loader once it is actually loaded
diff --git a/src/processout/processout.ts b/src/processout/processout.ts
index 3330d161..67625f5a 100644
--- a/src/processout/processout.ts
+++ b/src/processout/processout.ts
@@ -1395,6 +1395,7 @@ module ProcessOut {
       options: any,
       success: (data: any) => void,
       error: (err: Exception) => void,
+      iframeOverride?: IframeOverride,
     ): void {
       if (val instanceof Card || val instanceof CardForm)
         return this.tokenize(
@@ -1408,6 +1409,7 @@ module ProcessOut {
               options,
               success,
               error,
+              iframeOverride,
             )
           }.bind(this),
           error,
@@ -1420,6 +1422,7 @@ module ProcessOut {
         options,
         success,
         error,
+        iframeOverride,
       )
     }
 
@@ -1430,6 +1433,7 @@ module ProcessOut {
       options: any,
       success: (data: any) => void,
       error: (err: Exception) => void,
+      iframeOverride?: IframeOverride,
     ): void {
       this.handleCardActions(
         "PUT",
@@ -1439,6 +1443,8 @@ module ProcessOut {
         options,
         success,
         error,
+        undefined,
+        iframeOverride,
       )
     }
 
@@ -1460,6 +1466,7 @@ module ProcessOut {
       success: (data: any) => void,
       error: (err: Exception) => void,
       apiRequestOptions?: apiRequestOptions,
+      iframeOverride?: IframeOverride,
     ): void {
       const url: string = `invoices/${invoiceID}/capture`
       this.threeDSInitiationURL = `invoices/${invoiceID}/three-d-s`
@@ -1474,6 +1481,7 @@ module ProcessOut {
         success,
         error,
         apiRequestOptions,
+        iframeOverride,
       )
     }
 
@@ -1493,6 +1501,7 @@ module ProcessOut {
       success: (data: any) => void,
       error: (err: Exception) => void,
       apiRequestOptions?: apiRequestOptions,
+      iframeOverride?: IframeOverride,
     ): void {
       this.handleCardActions(
         "POST",
@@ -1503,6 +1512,7 @@ module ProcessOut {
         success,
         error,
         apiRequestOptions,
+        iframeOverride,
       )
     }
 
@@ -1521,6 +1531,7 @@ module ProcessOut {
       options: any,
       success: (data: any) => void,
       error: (err: Exception) => void,
+      iframeOverride?: IframeOverride,
     ): void {
       if (!options) options = {}
       options.incremental = true
@@ -1532,6 +1543,8 @@ module ProcessOut {
         options,
         success,
         error,
+        undefined,
+        iframeOverride,
       )
     }
 
@@ -1576,6 +1589,7 @@ module ProcessOut {
       success: (data: any) => void,
       error: (err: Exception) => void,
       apiRequestOptions?: apiRequestOptions,
+      iframeOverride?: IframeOverride,
     ): void {
       // returns this.hppInitialURL only once during the first call from HPP, then returns the endpoint
       const getEndpoint = (): string => {
@@ -1646,6 +1660,7 @@ module ProcessOut {
               success,
               error,
               apiRequestOptions,
+              iframeOverride,
             )
           }.bind(this)
 
@@ -1672,10 +1687,15 @@ module ProcessOut {
                     success,
                     error,
                     apiRequestOptions,
+                    iframeOverride,
                   )
                 }.bind(this),
                 error,
-                new ActionHandlerOptions(opts),
+                new ActionHandlerOptions(
+                  opts,
+                  undefined,
+                  opts !== ActionHandlerOptions.ThreeDSChallengeFlowNoIframe ? iframeOverride : undefined
+                )
               )
               break
 
@@ -1698,7 +1718,11 @@ module ProcessOut {
                   gReq.body = `threeDSMethodData={"threeDS2FingerprintTimeout":true}`
                   nextStep(gReq.token())
                 },
-                new ActionHandlerOptions(ActionHandlerOptions.ThreeDSFingerprintFlow),
+                new ActionHandlerOptions(
+                  ActionHandlerOptions.ThreeDSFingerprintFlow,
+                  undefined,
+                  iframeOverride,
+                ),
               )
               break
 
@@ -1708,7 +1732,11 @@ module ProcessOut {
                 data.customer_action.value,
                 nextStep,
                 error,
-                new ActionHandlerOptions(ActionHandlerOptions.ThreeDSChallengeFlow),
+                new ActionHandlerOptions(
+                  ActionHandlerOptions.ThreeDSChallengeFlow,
+                  undefined,
+                  iframeOverride,
+                ),
               )
               break