css: avoid image hover first time blinking

Question

I have an anchor that changes its background image when hovered with a class class-btn that contains a background-image.

When hovered, it

Answer 1

@Kristian's method of applying hidden 'content: url()' after the body didn't seem to work in Firefox 48.0 (OS X).

However, changing "display: none;" to something like:

body:after {
 position: absolute; overflow: hidden; left: -50000px;
 content: url(/path/to/picture-1.jpg) url(/path/to/picture-2.jpg);
}

... did the trick for me. Perhaps Firefox won't load hidden images, or maybe it's related to rendering(?).