Featured Image From URL

I have tried multiple Featured Image from URL plugins but none have worked. The plugin I used to use is no longer available, unfortunately it was the only one that worked. One of the plugins asked me to add .CSS, I am not sure if i did it right. I went into the Edit CSS tab and added this

img.nelioefi {
	min-width: 100px;
	min-height: 100px;
}

Anyone else having this problem? Also, if you have a plugin that you would recommend, please tell me.

My website is localsavage.com