Add "-webkit"-prefixed gradient for Safari
Add "-webkit"-prefixed gradient for Safari

Safari 6.0.5 still requires "-webkit" prefixes for gradients. Adding
this makes the background the desired gradient in Safari.


cribalik/marathon-ui,Raffo/marathon-ui,mesosphere/marathon-ui,yp-engineering/marathon-ui,Kosta-Github/marathon-ui,quamilek/marathon-ui,yp-engineering/marathon-ui,Kosta-Github/marathon-ui,janisz/marathon-ui,janisz/marathon-ui,pierlo-upitup/marathon-ui,cribalik/marathon-ui,watonyweng/marathon-ui,Raffo/marathon-ui,quamilek/marathon-ui,pierlo-upitup/marathon-ui,mesosphere/marathon-ui,watonyweng/marathon-ui