If I understand this correctly, the simplest way would be to use an iframe?
Put in an iframe on a page on mydomain.com and load the serviceportal.com in the iframe. Remove the borders of the iframe and
If you use NetScaler you will want to see these guides. The NetScaler How To Guides show administrators how to get NetScaler up and configured by providing instructions for common scenarios and some not so common ones.
In this article, I am going to show you how to simulate a multi-site Lab environment on a single Hyper-V host. I use this method successfully in my own lab to simulate three fully routed global AD Sites on a Windows 10 Hyper-V host.
Learn how to create flexible layouts using relative units in CSS. New relative units added in CSS3 include vw(viewports width), vh(viewports height), vmin(minimum of viewports height and width), and vmax (maximum of viewports height and width).