How to position images on dropped area using nth child in javascript

So basically your error is that you forgot the . in your css to select a class

so instead of (selecting element <box>)

.boxright1 box:nth-child(1) {

it should be (selecting class="box")

.boxright1 .box:nth-child(1) {

And add !important to your nth-child top and left values to make it override the initial #box_x values

But generally you should use some more elegant approach like a (flex)grid or sth