Blue box with question mark appeared in top menu! Help

Hi all.

Right, firstly I’m relit avidly new to this so be gentil, I’ve taught myself so far and sorted most things out but this is frustrating the hell out of me.

Recently I’ve noticed blue boxes with a question mark appear in the top menu of my ‘basix’ theme I’m running at https://www.pedalpowerabingdon.co.uk

It seems to only be when I have sub menus.

I’ve tried messing around with the style sheet.css and change the heights of the header etc with no luck however I’m not sure exactly if I’ve got the right section of code.

I’ve messed around with the header.php too and same as above.

I’ve uploaded the original style sheet.css and header folders from the original theme file too.

Am I missing something?

Please can you explain in laymen’s terms a fix if anyone can cel pas the person I brought this theme from has disappeared!

Many thanks

Stuart

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