JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="zonetexte" placeholder="tapez votre texte" autofocus ></textarea>

CSS

#zonetexte {
        font-size: 30px;
        line-height: 2;
         display:block; 
        width:100%; height:100%;
        padding:20px; box-sizing:border-box;
        border:6px solid #00CC00; border-radius:15px;
        padding:5px; box-sizing:border-box;
        text-align: left;
        color: blue;
        outline-style: none;
    }
#zonetexte:empty {
  font-size:15px;
  line-height:4
}