How to set placeholder text color on Firefox

input#myinput::-webkit-input-placeholder {
   color:#FFF; background-color:#CCC; 
}
input#myinput::-moz-placeholder { 
      color:#FFF; background-color:#CCC;  
    opacity: 1;
}
input#myinput:-moz-placeholder { 
      color:#FFF; background-color:#CCC; 
    opacity: 1;
}

input#myinput::-ms-input-placeholder { /* IE10+ */
      color:#FFF; background-color:#CCC; 
}     

input[type="text"]{
    width:170px; height:16px; padding:12px 5px; border:none; color:#848484; font:14px/14px 'Arial', Helvetica, sans-serif; text-align:center; background-color:#CCC;
}

<input id="myinput" type="text" placeholder="my placeholder" maxlength="30" name="myplaceholder">