The only eay you are ever going to get a 100% consistent result at any resolution is to draw the lines as lines within a post process.
Basically no matter how you code the shader on an object, the object itself is subject to scaling/perspective etc.
If instead you careate some outline sort of system in a postprocess, you can get accurate results all the time.
To learn how you can poke into the builtin wireframe view. Or, you can creatively use math and WPO to just generate a grid in the PP.
To learn how to generate a grid you can break down the default engine material, which is a dual color grid.