JSFiddle - React, Tailwind, and code Playground

HTML

<div id="partie1" class="partie">
  <div class="center">
    <p class="para">
      Mon paragraphe
      </p>
    <h3>Titre H1 : Mon titre</h3>
  </div>
</div>
<div id="partie2" class="partie">
  <div class="center">
    <p class="para">
      Mon paragraphe
    </p>
    <h3>Mon titre</h3>
  </div>
</div>

CSS

* {
  margin:0;
  border:solid;
}
.center {
  width: 1000px;
  margin: 0 auto;
}

#partie1 h3 {
  width: 450px;
  display: inline-block;
  font-family: Arial;
  font-size: 60px;
  margin-left: 150px;
  vertical-align:top;
}

.para {
  width: 200px;
  display: inline-block;
}

.titre {
  margin-top: 50px;
}

#partie2 h3 {
  width: 450px;
  display: inline-block;
  font-family: Arial;
  font-size: 20px;
}