Saas placeholder mixin

gistfile1.sass

@mixin placeholder {
    &::-webkit-input-placeholder {
        @content;
    }
    &:-moz-placeholder { /* Firefox 18- */
        @content;  
    }
    &::-moz-placeholder {  /* Firefox 19+ */
        @content;  
    }
    &:-ms-input-placeholder {  
        @content;  
    }
    &.placeholder { /* for use with jQuery placeholder plugin: https://github.com/mathiasbynens/jquery-placeholder */
        @content;
    }
}