Impossible to declare box-shadow with wp.customize?

I’m trying to put a section in the customizer where you can choose how to put a box-shadow in a h1. The problem is that i need to write the whole box-shadow box at once, is not like border where you can split in border-top, border-color, border-style, border-with, etc. Then, i need to get some css values different than the one im changing at that moment. Well, i dont know if i explained my self properly. You can see what i mean in the following example code (it’s just an example, this code doesnt work):