At the top of my website math.gr there is a horizontal line, with a small black bold arrow ‘^’ on the left. What is this line?
See the image: 
-
This topic was modified 2 years by
newpaperwptheme. Reason: I forgot the image
Hi,
For the issue with the icon please resave the settings from the theme panel https://imgur.com/Pz3CjBz
Have a great day!
My theme panel looks different than yours: 
-
This reply was modified 2 years by
newpaperwptheme. Reason: I forgot the image
I have built my website. The horizontal line was not there. It appeared suddenly. If I press save, the header of my website will be destroyed and I must build it from the beginning.
-
This reply was modified 2 years by
newpaperwptheme. Reason: I forgot the image
I activated the tagdiv standard pack and my theme panel, now, is like yours.
But, I have built my website a long time ago. The horizontal line was not there. It appeared suddenly.
If I press save, the header of my website will be destroyed and I must build it from the beginning.
You say, without header there is no issue. And I must build it from the beginning. Cutting the head to cure headache?
My site before

My site after

Yes ‘header template default Pro’. I went back and the horizontal line disappeared.
Thank you!