Transition looks to be operating well there
Is it possible to make the selecting square more horizontal shape than vertical. Make it wider like the marquees and not so high.
Also to put the blue square around all of the marquees. Ok for the marquee to go a bit outside the square.
Then the square that is highlighting the currently selected marquee to have a yellow glow.
Also for all the marquees that are not selected to be in black and white. Only the one that is selected to be in full color and have the yellow glow. The ones that are not selected to have the blue square border and be black and white no color.