修改input placeholder色值

::-webkit-input-placeholder { /* WebKit browsers */

            color:    #c6c6c6;

        }

        :-moz-placeholder { /* Mozilla Firefox 4 to 18 */

            color:    #c6c6c6;

        }

        ::-moz-placeholder { /* Mozilla Firefox 19+ */

            color:    #c6c6c6;

        }

        :-ms-input-placeholder { /* Internet Explorer 10+ */

            color:    #c6c6c6;

        }