As it's described here in RFC (see 1. Visual Changes) we need to prepare this page and make it more structured if we want to add new things like preview panel in the future.

RFC suggests the following list of changes

• Increase density of information (primary by not using spacing as separation element, and use backgrounds instead)
• Remove decorative elements like separation between different blocks on the page
• Support slim/closed version of filters panel (when other panel such as preview panel is open)