Animate .gif on rollover?

You will need to find the block- ID for each image, and do this.

You will also need a static and dynamic image uploaded in the files and to link them in the code.

So the last 2 blocks of code will need to be repeated 20 times for 20 images, changing the block- ID

.thumb-image.loaded {
    display: none;
}

#block-yui_3_17_2_1_1592964324330_57866 .image-block-wrapper.has-aspect-ratio {
    background: url("STATIC IMAGE");
}

#block-yui_3_17_2_1_1592964324330_57866 .image-block-wrapper.has-aspect-ratio:hover {
    background: url("PLAYING IMAGE");
}