None of your images work and your post is not descriptive enough of the issue without them.
I'll tell you this though -- fixed size root means it can't be crisp. Whether the resolution is 1280x720 or 2560x1440, your UI will have the same size relative to the height of the screen, meaning your pixels will be either bigger or smaller. The only way to have a truly crisp UI, is to have it be using a Flexible style and not limiting its minimum/maximum height. This means the UI will look bigger or smaller, depending on the resolution and it will be up to you to use a higher definition atlas when needed.
