设置placeholder的样式

:-moz-placeholder {
/* Mozilla Firefox 4 to 18 */
color: #f00;
}

::-moz-placeholder {
    /* Mozilla Firefox 19+ */
    color: #f00;
}

input:-ms-input-placeholder,
textarea:-ms-input-placeholder {
    color: #f00;
}

input::-webkit-input-placeholder,
textarea::-webkit-input-placeholder {
    color: #f00;
}