admin: fix jumpyness when a modal is shown (move overflow-y to body; make the navbar not fixed to top)
admin: fix jumpyness when a modal is shown (move overflow-y to body; make the navbar not fixed to top)

d5ve/mailinabox,choltha/mailinabox,d5ve/mailinabox,d5ve/mailinabox,mail-in-a-box/mailinabox,choltha/mailinabox,m4rcs/mailinabox,m4rcs/mailinabox,jprice/mailinabox,ianberinger/mailinabox,nstanke/mailinabox,choltha/mailinabox,mail-in-a-box/mailinabox,Neopallium/mailinabox,Neopallium/mailinabox,nstanke/mailinabox,ianberinger/mailinabox,nstanke/mailinabox,m4rcs/mailinabox,m4rcs/mailinabox,jprice/mailinabox,Neopallium/mailinabox,ianberinger/mailinabox,choltha/mailinabox,ianberinger/mailinabox,d5ve/mailinabox,jprice/mailinabox,d5ve/mailinabox,mail-in-a-box/mailinabox,Neopallium/mailinabox,nstanke/mailinabox,jprice/mailinabox,nstanke/mailinabox,jprice/mailinabox,Neopallium/mailinabox,m4rcs/mailinabox,mail-in-a-box/mailinabox,ianberinger/mailinabox,choltha/mailinabox