input placeholder字体

::-webkit-input-placeholder { /* WebKit, Blink, Edge */
  font-size:9px;
}
:-moz-placeholder { /* Mozilla Firefox 4 to 18 */
  font-size:9px;
}
::-moz-placeholder { /* Mozilla Firefox 19+ */
   font-size:9px;
}
:-ms-input-placeholder { /* Internet Explorer 10-11 */
   font-size:9px;
}

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