JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" name="customPlaceholder" id="customPlaceholder" placeholder="to be styled" value=""/>

CSS

input#customPlaceholder::-webkit-input-placeholder {
   text-decoration: line-through;
}
input#customPlaceholder::-moz-placeholder {
   text-decoration: line-through;
}
input#customPlaceholder:-ms-input-placeholder {  
   text-decoration: line-through;
}