It is possible to make the body display:none and have one children element display:block ?
I'm not sure how to make my question correctly formulated. I just want to hide the body content and then display a div element only.
By general rule, if a parent element has "display:none" property, no child can be rendered on a page, so the answer is "no".
You may consider to put that children element outside its parent, while being outside body element may affect the validation of your html code.