Bootstrap导航栏下拉菜单显示异常问题求助

将Bootstrap下拉菜单加入自定义导航栏后出现两个问题：

• 下拉菜单选项需鼠标悬停才可见
• 下拉菜单文本为蓝色，且不希望悬停时文本仍保持蓝色

尝试移除该元素的Bootstrap CSS但未解决，相关代码如下：

自定义CSS代码 #

.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 999;
}

.top-navbar {
    background-color: #333;
    height: 40px;
}

.top-navbar-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: flex-end;
    align-items: center;
    height: 100%;
}

.top-menu {
    list-style: none;
    display: flex;
    margin: 0;
    padding: 0;
}

.top-menu li {
    margin-right: 20px;
}

.top-menu li:last-child {
    margin-right: 0;
}

.top-menu li a {
    text-decoration: none;
    color: #fff;
    font-size: 12px;
    font-weight: 600;
}

.main-navbar {
    background-color: #fff;
    height: 80px;
    box-shadow: 0px 4px 4px rgba(0, 0, 0, 0.1);
}

.main-navbar-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.logo-container {
    width: 80px;
}

.logo {
    width: 100%;
    height: 100%;
}

.menu-container {
    display: flex;
    align-items: center;
}

.menu {
    list-style: none;
    display: flex;
    margin: 0;
    padding: 0;
}

.menu li {
    margin-right: 20px;
}

.menu li:last-child {
    margin-right: 0;
}

.menu li a {
    text-decoration: none;
    color: #333;
    font-weight: 600;
}

.icons {
    display: flex;
    align-items: center;
    margin-left: 20px;
}

.cart-icon {
    margin-right: 20px;
    width: 100px;
    height: 100px;
}
.logo-container {
  width: 78px;
  height: 100%;
  display: flex;
  align-items: center;
}

.logo {
  width: 100%;
  height: auto;
}

HTML/PHP代码 #

<header class="header">
    <nav class="top-navbar">
        <div class="top-navbar-container">
            <ul class="top-menu">
                
                <?php
        if(isset($_SESSION['auth']))
        {
            ?> 
 <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownMenuLink" role="button" data-bs-toggle="dropdown" aria-expanded="false">
            <?= $_SESSION['auth_user']['name'] ?>
          </a>
          <ul class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
            <li><a class="dropdown-item" href="#">Action</a></li>
            <li><a class="dropdown-item" href="#">Another action</a></li>
            <li><a class="dropdown-item" href="logout.php">Logout</a></li>
            

            <?php
        }
        else
        {
            ?>
 <li class="nav-item">
          <a class="nav-link" href="register.php">Register</a>
        </li>
        <li class="nav-item">
          <a class="nav-link" href="login.php">Login</a>
        </li>
        
            <?php
        }
        ?>
            </ul>
            <div class="icons">
                <a href="cart.html"><i class="fa-solid fa-cart-shopping fa-xl" style="color: #0000ff;"></i></a>
            </div>
        </div>
    </nav>
    <nav class="main-navbar">
        <div class="main-navbar-container">
            <div class="logo-container">
                <img src="Noah Grocery Logo.png" alt="Grocery Store Logo" class="logo">
            </div>
            <div class="menu-container">
                <ul class="menu">
                    <li><a href="index.html">Home</a></li>
                    <li><a href="shop.html">Shop</a></li>
                    <li><a href="support/support.html">Support</a></li>
                </ul>

            </div>
        </div>
    </nav>
</header>

注：代码片段未引入Bootstrap，Bootstrap在站点的其他文件中加载。

1. 修正HTML结构错误 #

原代码中dropdown-menu被错误放置在top-menu闭合标签外，导致结构异常，这是下拉显示异常的核心原因之一。修正后需确保.dropdown-menu嵌套在对应的.dropdown父元素内，修正后的代码见下方完整HTML/PHP块。

2. 覆盖Bootstrap下拉菜单样式 #

添加以下CSS代码，强制覆盖Bootstrap默认样式，解决文本颜色及悬停问题：

/* 控制下拉菜单显示逻辑，配合Bootstrap的show类 */
.dropdown-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    z-index: 1000;
    background-color: #fff;
    border: 1px solid rgba(0,0,0,.15);
    border-radius: 0.25rem;
}

.dropdown.show .dropdown-menu {
    display: block;
}

/* 修改下拉菜单项默认颜色 */
.dropdown-item {
    color: #333 !important;
    padding: 0.5rem 1rem;
}

/* 修改悬停时的文本颜色与背景 */
.dropdown-item:hover {
    color: #fff !important;
    background-color: #333 !important;
    text-decoration: none;
}

3. 完整修正后的HTML/PHP代码 #

<header class="header">
    <nav class="top-navbar">
        <div class="top-navbar-container">
            <ul class="top-menu">
                <?php
                if(isset($_SESSION['auth']))
                {
                    ?> 
                    <li class="nav-item dropdown">
                        <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownMenuLink" role="button" data-bs-toggle="dropdown" aria-expanded="false">
                            <?= $_SESSION['auth_user']['name'] ?>
                        </a>
                        <ul class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
                            <li><a class="dropdown-item" href="#">Action</a></li>
                            <li><a class="dropdown-item" href="#">Another action</a></li>
                            <li><a class="dropdown-item" href="logout.php">Logout</a></li>
                        </ul>
                    </li>
                    <?php
                }
                else
                {
                    ?>
                    <li class="nav-item">
                        <a class="nav-link" href="register.php">Register</a>
                    </li>
                    <li class="nav-item">
                        <a class="nav-link" href="login.php">Login</a>
                    </li>
                    <?php
                }
                ?>
            </ul>
            <div class="icons">
                <a href="cart.html"><i class="fa-solid fa-cart-shopping fa-xl" style="color: #0000ff;"></i></a>
            </div>
        </div>
    </nav>
    <nav class="main-navbar">
        <div class="main-navbar-container">
            <div class="logo-container">
                <img src="Noah Grocery Logo.png" alt="Grocery Store Logo" class="logo">
            </div>
            <div class="menu-container">
                <ul class="menu">
                    <li><a href="index.html">Home</a></li>
                    <li><a href="shop.html">Shop</a></li>
                    <li><a href="support/support.html">Support</a></li>
                </ul>
            </div>
        </div>
    </nav>
</header>

关键注意事项 #

• 确保Bootstrap的JS文件已正确加载，data-bs-toggle="dropdown"需要JS支持才能触发下拉显示
• 将自定义CSS放在Bootstrap CSS之后加载，或使用!important提升样式优先级

内容的提问来源于stack exchange，提问作者Random Coder 16