Product Unavailable Options in Product Store

Site URL: https://reindeer-sailfish-bkep.squarespace.com/prints/p/alaskanspines

Hello, 

I am looking for help in the store page. 
As it is a print shop, I have a number of different options available for each product. 
I wanted to know if there is a work around so that when you put a product which is unavailable - for example in my store: Brushed Aluminium is not available in 20 x 30 - rather than it saying "Unavailable" at the top, the option could be greyed out / not clickable - so that the consumer knows that they can not purchase that product. 
I have done a work around - by adding in the products on the sizes but it is a bit messy. I would rather just have the sizes. 

Screenshots to try and help explain what I mean. 
Website: https://reindeer-sailfish-bkep.squarespace.com/prints/p/alaskanspines
PW: help

Thank you. 
Beanie