gistfile1.txt

<style>
#interstitial_image_320, #interstitial_image_700 {
display: none;
}

#wapa_interstatial_wrapper {
position: fixed;
top: 50%;
left: 50%;
transform: translate(-50%,-50%);
padding: 5px;
box-sizing: border-box;
background: white;

}
#wapa_interstatial_close {
position: absolute;
top: 9px;
right: 10px;
cursor: pointer;
width: 15px;
height: 15px;
background-color: #FFF;
z-index: 600;
display: flex;
justify-content: center;
align-items: center;
}

#wapa_interstatial_close:after {
     content: '\d7';
    font-size: 20px;
}

@media (max-width: 767px) {
#interstitial_image_320 { 
display: block;
}
}

@media (min-width: 768px) {
  #interstitial_image_700 { 
  display: block;
}
}

</style>

<div id="wapa_interstatial_wrapper">
<a target="_blank" href="%%CLICK_URL_UNESC%%[%destiantionUrl%]">
<img id="interstitial_image_320" width="320px" height="480px" src="%%VIEW_URL_ESC%%[%320x480image%]" />
<img id="interstitial_image_700" width="700px" height="500px" src="%%VIEW_URL_ESC%%[%700x500image%]" />
</a>
<div id="wapa_interstatial_close" onClick="window.top.document.body.className = 'interstatial-set'"></div>
 <div ></div>
</div>