[[ $(hostname) == "tardis" ]] && hostcolor=red
[[ $(hostname) == "shada" ]]  && hostcolor=green
PROMPT="%(?..%{$fg_bold[white]%}[%?])%{$reset_color%}[%D{%k:%M} %n@%{$fg[$hostcolor]%}%m%{$reset_color%}]%# "
RPROMPT="%{$fg[green]%}%~%{$reset_color%}"