Html – [Solved]Having trouble adjusting the height of my card in bootstrap

<div class="card border-dark bg-white text-dark" style="width: 400px; height: auto; margin :10px auto ">
        <div class="card-header">
            <h3>Register to REFILM</h3>
        </div>
        <div class="card-body">
            <form action="/register" method="post">
                <div class="mb-3">
                    <input autocomplete="off" autofocus type="text" class="form-control" name="username" placeholder="Username">
                </div>
                {% if username_error %}
                    <div class="alert alert-danger" role="alert">
                    {{ username_error }}
                    </div>
                {% endif %}
                <div class="mb-3">
                    <input type="password" class="form-control" name="password" placeholder="Password">
                </div>
                {% if password_error %}
                    <div class="alert alert-danger" role="alert">
                    {{ password_error }}
                    </div>
                {% endif %}
                <div class="mb-3">
                    <input type="password" class="form-control" name="confirmation" placeholder="Confirm password">
                </div>
                {% if confirmation_error %}
                    <div class="alert alert-danger" role="alert">
                    {{ confirmation_error }}
                    </div>
                {% endif %}
                <div class="col text-center">
                    <button type="submit" class="btn btn-primary">Register</button>
                </div>
            </form>
        </div>
    </div>

I’m creating a registration window using card properties in bootstrap. But it’s very strange because the height of the card fills the screen.

I’ve tried settings like height: auto on parent tag and child tag, but it’s still the same.