Hi henryxuato,
It will be quitely complicated to edit the .js of our JA Content Popup module since our developer use the javascript functions to count the width of popup view when changing the width of popup view in the module’s backend. And your modification is easy to be overwritten when updating our module.
In this case, i suggest you can use the overridden css style to set the fixed max-width of popup view, that make the widht not spread to 100% by trying to put below codes into templates/ja_onepage/css/custom.css file:
div#yoxview {
max-width: 450px;
width: 450px !important;
}
iframe#bd-popup-iframe {
width: 100% !important;
}
Adjust the width of div#yoxview until you get perfect.