<input type="text" placeholder="blue placeholder...">

::placeholder {
  color: #007FFF;
  opacity: 1;
}

:-ms-input-placeholder { 
 color: #007FFF;
}

::-ms-input-placeholder { 
 color: #007FFF;
}

<iframe src="https://www.netbax.net/tab/creation/placeholder.html" style="width: 550px; height:550px;" frameborder="0"></iframe>