<form name="joinclass_form">
    <div class="card mx-auto col-10">
        <div class="card-header">Join a Class</div>
        <div class="card-body">
        <label class="form-check-label" for="given_code"> Class code</label>
        <input type="text" name="given_code" class="form-control" required>
        <p></p>
        <div class="alert alert-danger mb-3 error error--hidden">Invalid Code</div>
        </div>
        <button type="submit" class="btn btn-primary text-center">Join Class</button>
    </div>
</form>