Lightbox (Fancybox) radius

Copy and paste to Before </body>

<script>
$(document).ready(function () {
        $("#fancybox-outer").corner("35px");
        $("#fancybox-content").css("border-color", "red").corner("25px");
    });
 </script>

Change border-color and 35px and 25px to your radii

Copy and paste to <head></head>

<style>
.fancybox-bg, #fancybox-wrap {
  display: none
}
</style>

<script src="jquery.corner.js"></script>

Download jquery.corner.js from here https://malsup.com/jquery/corner/