The side bar is usually a temporary state, but when you change the cards to just one option, this not something the user requested (nor was expecting it to change) for the items to change from multiple listings to just one
There’s few ways you can approach this, the sidebar either slides on top of the content and sidebar returns to it original state after you’re done with the sidebar
or it stays put and pushes the content to the right where the news and stacker news section kinda gets hidden and your main content, which is items for sale remains visible and have cards that shows everything the user wants to see.
