Redmine

If the body is dark then the content parts show up only until 600px height. This height is not moving further down if
content gets extended in your personalized page.

i.e. if you use calendar width 100%
and below 2 50% boxes with content i.e. latest news, open issues ...
then those part won't have a white background

Solution would be to have another div id=wrap after body

The you could assign

body {background: black; margin:auto; width:974px}
#wrap {background: white}

at the moment this isn't possible without editing the templates itself but after an update those templates would get
overwritten as only the css is stored in themes.