Is There anyways to change the theme of the lightbox style?

Im trying so hard to change the old look of this lightbox base on my theme which is light and minimalist. I want to remove the white borders/containers (which I did) and to change the close, next and prev button images. I did somehow change the close but its hard to change the left and right images thru css.

My Question is: is there any easier ways to change the look and feel of this old looking lightbox?

Unfortunately, this is the only lightbox that works on my theme so I’m kinda stucked.

thanks and regards

https://www.ads-software.com/extend/plugins/wp-jquery-lightbox/