CSS怎样修改input和textarea中placeholder的样式

::-webkit-input-placeholder { /* WebKit browsers */
    color: #222222;
}
:-moz-placeholder { /* Mozilla Firefox 4 to 18 */
    color: #222222;
}
::-moz-placeholder { /* Mozilla Firefox 19+ */
    color: #222222;
}
:-ms-input-placeholder { /* Internet Explorer 10+ */
    color: #222222;
}