.background-repeat {
background-repeat: no-repeat, repeat, repeat-x, repeat-y, round, round space, space, space round;
}
repeat 相当于repeat repeat
repeat-x 相当于repeat-x no-repeat
repeat-y 相当于no-repeat repeat
space 相当于space space
round相当于round round
no-repeat相当于no-repeat no-repeat
也就是说，在background-repeat取值是，可以将x和y的值任意组合，比如round space、space round、round repeat-y之类的。别的不说，我们来看一个round space的组合

参考：http://www.w3cplus.com/css3/css3-background-repeat-space-round.html