Removing black box in left Table of Contents

[Joseph The Grave]

Hi. How do I gt rid of the black box in the left Table of Contents pane in e-book reader? I can drag it to make it smaller but want to remove it entirely. See attached photo to show what I mean.

Edited: sorry, I just realized that the black box is reserved for the Search results so I'd like to change my question to: is there a way to make it auto-hide until I use search?

https://i.imgur.com/PQr70OP.jpg

[DNSB]

You can use the ...... between the search box and ToC to resize. See attached image. Through most of calibre's UI, those .. indicate handles. To close it, you can click in the x in a box in the upper right hand corner of the search window.