How to collaborate with UX developers

Currently my team (a product team) designs mockups of UI impovements and enhancements using screenshots painfully stitched together. We then pass them off to the technology team who tries to replicate them in their development tools.
It's a slow and iterative process because their replications are never the designs we create (and we always want the color to be slightly different, or the shape, position, etc).

Are there simpler ways of doing this, where, we create a basic front end and let them plug it into the back end?