This has been frustrating me for a while... When I right clicked a CSS rule in the Computed tab and then cliked "Use in Command Line", this opened up a special bottom console that has no close button or any other button to rehide it. The screenshot shows a red button at the left corner, but this just shows the history of previous commands:
The little down-arrow-triangle on the current tab does not allow to expand the tab to full height either, the only tab that this bottom console does not show up is the Console tab.
The only way I found to circumvent/minimize this problem is to reduce the size of this bottom console. Still, it doesn't make much sense to do this...