Grey horizontal line at the top of the product page

Hello there all and hope you are all doing well 🙂

I wonder can anyone help me, there is a grey horizontal line that appears at the top of the store page, see screen grab below,

Would anyone have any CSS code I could use to delete this? Not really wild on it to be honest and would prefer if it would go!
it's part of the template and I can't remove it unless I have code...

Thanks so much!!!