Base for refrigerator wine shelf

I have a wine refrigerator that has shelves for wine bottles – image on this question.

I want to use this refrigerator and its shelves as a regular refrigerator. So I need to put something on the shelf to make it flat so it can hold anything. The inner (usable) part of this shelf is 23" x 17".

At its simplest I think could have some 1/4" plywood cut to those dimensions and simply put them on top.

However this doesn't feel like the correct solution to me. How would I best convert these shelves to a flat surface that can hold any shaped item like a regular refrigerator?