unwanted shaky image transition on hover

I am using Decode theme https://www.ads-software.com/themes/decode version 3.0.4, which comes with transitions, which is cool.

But on one page (maybe others I haven’t yet discovered), it causes the image to move slightly when mouseover and then move again when mouseout.

.entry-content a > img {
    opacity: 1;
    transition: opacity 0.25s ease-out 0s;
}

On other pages with linked images, it works fine: mouseover, image fades slightly; mouseout, image is restored.
But on this one particular page, when you run the mouse over the image, the entire image shifts one or two pixels to the left as it fades.Once it has run the transition, it moves itself back in place. When you remove the mouse, it shifts left again, and then moves back, as it restores the opacity.

Examples:
Page where it works as expected: https://www.leeaaron.com/wp2012/media/photo-galleries/lee-friends/
Page where it is doing this weird thing: https://www.leeaaron.com/wp2012/we-love-metal/

Any ideas?

Thanks!