JSFiddle - React, Tailwind, and code Playground

HTML

<form>
 <input type="text" name="fname" placeholder="First name"><br>
</form>

CSS

body{background:black}
input{height:30px;opacity:.5;}
input::-webkit-input-placeholder {
     color: black; /*Change the placeholder color*/
     opacity: 0.5; /*Change the opacity between 0 and 1*/
}