XF 1.5 banner in header ad position causes white triangle

Mr Lucky

Well-known member
Two related questons:

(1) I have a banner in the header with a width of 100% (height 50px) so it appears above the logo.

However this causes a white triangle to appear above the navigation.

I assume this means I have to compensate somewhere for the extra 100px, I have tried adding that to the logo height in style properties, but that doesn't fix it (just adds space above and below the logo.

(2) Alternatively if I make the banner narrower (300px) and float right, the issue (as you might expect) only occurs when the mobile width reduces to the point that the banner goes above the logo. Is it the same solution for both examples?

This is with default style and addons disabled, can anyone help please - I know the answer must be staring me in the face, thanks.