How to set the color of “placeholder” text?

textarea::-webkit-input-placeholder {  color: #999;}

::-webkit-input-placeholder { /* WebKit browsers */
    color:    #999;
}
:-moz-placeholder { /* Mozilla Firefox 4 to 18 */
    color:    #999;
}
::-moz-placeholder { /* Mozilla Firefox 19+ */
    color:    #999;
}
:-ms-input-placeholder { /* Internet Explorer 10+ */
    color:    #999;
}

input:-moz-placeholder { color: #aaa; }
 textarea:-moz-placeholder { color: #aaa;}