Layout Gap Without Featured Image

Hello, i’ve been trying to resolve a layout issue but haven’t been able to fix it so far.

On single posts, there is a grey area above the white content area (post content and sidebar). When the featured image is displayed inside the post, everything aligns perfectly and the layout looks correct.

However, when the option to disable the featured image inside single posts is enabled, a small empty gap remains in that grey area, and the alignment is no longer perfect. It looks like space is still being reserved for the featured image even though it’s not rendered.

It’s a small visual detail, but I’ve spent several days trying to trace it and haven’t been able to fix it via CSS or template overrides. Could you please advice?