Bootstrap 4 導航欄固定頂部問題：為什么它會創建一個空白區域

Question

嗨，我在導航欄中遇到了一個問題，它會創建一個空白區域：截圖html 代碼：

    <div class="header">
    <div class="overlay"></div>
    <nav class="navbar fixed-top navbar-expand-lg navbar-light bg-light">
        <a class="navbar-brand" href="#">Creative Agency</a>
        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
            <span class="navbar-toggler-icon"></span>
        </button>

        <div class="collapse navbar-collapse" id="navbarSupportedContent">
            <ul class="navbar-nav ml-auto">
                <li class="nav-item active">
                    <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#">Watch Video</a>
                </li>
                <li class="nav-item dropdown">
                    <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                    Demo Pages
                    </a>
                    <div class="dropdown-menu" aria-labelledby="navbarDropdown">
                        <a class="dropdown-item" href="#">Creative Agency</a>
                        <a class="dropdown-item" href="#">Travel Agency</a>
                    </div>
                </li>
                <li class="nav-item dropdown">
                    <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                    Blocks
                    </a>
                    <div class="dropdown-menu" aria-labelledby="navbarDropdown">
                        <a class="dropdown-item" href="#">Menu Pages</a>
                        <a class="dropdown-item" href="#">Haeders</a>
                        <a class="dropdown-item" href="#">Pages</a>
                        <a class="dropdown-item" href="#">Images & Videos</a>
                        <a class="dropdown-item" href="#">Team</a>
                        <a class="dropdown-item" href="#">Counters</a>
                    </div>
                </li>
            </ul>
        </div>
        <ul class="social-links list-unstyled">
            <li><a href="#"><i class="fab fa-twitter"></i></a></li>
            <li><a href="#"><i class="fab fa-facebook-f"></i></a></li>
            <li><a href="#"><i class="fab fa-instagram"></i></a></li>
        </ul>
    </nav>
    <div class="container">
        <div class="heading text-center">
            <h1>We are creative agency</h1>
            <p>Our professional team of designers will help you to create a unique image of your company, which will distinguish it from competitors and attract new customers.</p>
        </div>
    </div>
</div>

我怎樣才能使導航欄固定（在頂部）而不會出現這個問題！

我使用 Bootstrap 4

注意：為 body 添加 padding-top 並不能解決這個問題！

Answer 1

我通過 addign 解決了這個問題

padding-top: 48px;

到標題！