<div class="form-container">
  <div class="email-container">
    <label for="abo-newsletterSubscriber">Votre adresse email (exemple : [email protected])</label>
    <input id="abo-newsletterSubscriber" type="email" name="email" autocomplete="email">
  </div>
</div>

.form-container {
  display:flex;
  justify-content:center;
  align-items:center;
  width: 30rem;
  height: 10rem;
  padding: 1.5%;
  box-sizing: border-box;
  -webkit-border-radius: 0.5rem;
  -moz-border-radius: 0.5rem;
  border-radius: 0.5rem;
  }

.form-container:focus-within {
  outline: 0.1rem solid #2d1e9f;
  background: #F9EAFF;
}

label,
input {
  display: block;
}

label {
  margin-bottom: 0.3rem;
}