macos - Vim zenburn doesn't work under screen in mac

Question

I'm trying to use zenburn on OSX under vim. However, whenever I use vim under screen, the background is black instead of grey. Are there color settings I need to set in screen?

Here's my screenrc:

vbell off
vbell_msg "Ring"

# detach on hangup
autodetach on

# don't display copyright page
startup_message off

# scroll back
defscrollback 10000

# setup the caption
hardstatus alwayslastline "%{-b gk}%-w%{+b kg}%50>%n %t%{-b gk}%+w %=%C%<"

# right/left bindings
bindkey "^[[c" next
bindkey "^[[d" prev
bindkey "^[[b" focus

# screen 256 color support
attrcolor b ".I"
termcapinfo xterm 'Co#256:AB=\E[48;5;%dm:AF=\E[38;5;%dm'
defbce "on"

# Make terminal scrolling work properly with screen
termcapinfo xterm-256color|xterm-color|xterm|xterms|xs|rxvt ti@:te@

shell -${SHELL}