First thanks fot this great theme. 
On the blog page (either blogpage or single post) – i can’t find the way to change

• the black background of the page. and to set it to #F1F1F1 for instance
• the kind of green color for the title to change to #004DFE for instance (In your demo page-  http://pluton.themeart.co/markup-and-formatting/ it’s the color used for “Markup And Formatting” for example).

Thanks for your help !