Gif in 3D flipbook

Hello,
I am trying to show a gif in my pdf file via your plugin.

In CSS I placed the following code:

.gif1 {
background-image: url('https://mysite.com/wp-content/uploads/2020/12/felix.gif');
width: 360px;
height: 270px;
position: absolute;
left: 100px;
top: 100px; 
}

In HTML I put the following:
<div class="gif1"></div>

I now see the box with the correct dimensions on the page, I also see the movement of the Gif, but the image is displayed much too large.

How can I fit this Gif, which actually has the same dimensions as the “box” (360×270) shown?

Thanks!