I want to use flatpickr, but the placeholder is not displayed properly on the input form.

I'm loading the code below, but the placeholder isn't displayed in the input form
It is displayed as year/month/day.
Corresponding source code
<link rel = "stylesheet" href = "https://cdn.jsdelivr.net/npm/flatpickr/dist/flatpickr.min.css">
<script src = "https://cdn.jsdelivr.net/npm/flatpickr"></script>
<input type = "text" placeholder = "Select Date ..">
    flatpickr ("# flatpickr");

I think it's a rudimentary thing, but I would like advice.