Make sure you have been created your attributes: capacity, price, color, type etc. with input DROPDOWN. Then, check your settings (see below) and try it again.
Use In Layered Navigation —— Filterable (with results) OR Filterable (no results)
Use In Search Results Layered Navigation —— Yes
Visible on Product View Page on Front-end —— Yes
Used in product listing —— Yes
Used for sorting in product listing —— Yes
I noticed you have a link RSS Feed (footer) that points to /about-magento-demo-store. I am sure you don’t want to show that to your customers.