Centre Logo

That is better- I deleted a rogue "menu item separator" element in my menu.

Next, how do I get rid of the black strip and make the menu transparent? Or should I start a new thread?

The black strip you see is the background color of Primary navigation.

You can remove its color through Appearance > Customize > Colors and look for Primary Navigation's Navigation Background. :)

It's this one - https://share.getcloudapp.com/NQu7QzAZ

Brilliant, thanks.

My menu stretches across the entire width of a my screen, is there any way that I can get to stretch across just the width of my blog- from the edge of the left column to the far edge of the sidebar on the right. See the image in private information. The red arrow marks the ideal width...

You would need to set the Customizer > Layout > Header --> Inner Width to Contained. But you may find that is too narrow for all your menu items as the logo takes quite a lot of space.

Brilliant. I have changed my logo. Thanks

Glad we could be of help!