Data de padrão exigida html

<form>
  <label>Enter your birthday:
    <input type="date" name="bday" required pattern="\d{4}-\d{3}-\d{2}">
    <span class="validity"></span>
  </label>
  <p>
    <button>Submit</button>
  </p>
</form>
yahya AAMMAR