Since updating to the new blog I can't seem to shift this background colour and I've looked at all the design options. Hoping this is something that can be fixed cause I've spent ages redesigning my website only to be let down by this on my blog posts, even in edit mode, as well as the fact it's seriously basic in terms of formatting - guess I probably should have came here first before updating to the new blog D:
Hi!
In the Post page settings please go to the Design --> Post --> Post background and color: