JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" placeholder="some cool text"/>

CSS

input:focus::-moz-placeholder {
    opacity: 0.1;
}
input:focus::-webkit-input-placeholder {
	 opacity: 0.1;
}
input::-moz-placeholder {
    opacity: 1;
	transition: opacity 1s;
}
input::-webkit-input-placeholder {
    opacity: 1;
    transition: opacity 1s;
}