下面的div上的bootstrap 4下拉菜單

Question

我試圖讓bootstrap 4響應式頂級導航出現在我的容器div上，但沒有運氣，我似乎無法找到解決方案。

這是頂級導航儀的工作原理
W3Schools編輯器

這是我的代碼的jsfiddle
的jsfiddle

 function myFunction() { var x = document.getElementById("myTopnav"); if (x.className === "topnav") { x.className += " responsive"; } else { x.className = "topnav"; } } 

  /* Add a black background color to the top navigation */ .topnav { background-color: #333; overflow: hidden; } /* Style the links inside the navigation bar */ .topnav a { float: left; display: block; color: #f2f2f2; text-align: center; padding: 14px 16px; text-decoration: none; font-size: 17px; } /* Add an active class to highlight the current page */ .active { background-color: #4CAF50; color: white; } /* Hide the link that should open and close the topnav on small screens */ .topnav .icon { display: none; } /* Dropdown container - needed to position the dropdown content */ .dropdown { float: left; overflow: visible; } /* Style the dropdown button to fit inside the topnav */ .dropdown .dropbtn { font-size: 17px; border: none; outline: none; color: white; padding: 14px 16px; background-color: inherit; font-family: inherit; margin: 0; } /* Style the dropdown content (hidden by default) */ .dropdown-content { display: none; position: relative; background-color: #f9f9f9; min-width: 160px; box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2); z-index: 2; } /* Style the links inside the dropdown */ .dropdown-content a { float: none; color: black; padding: 12px 16px; text-decoration: none; display: block; text-align: left; } /* Add a dark background on topnav links and the dropdown button on hover */ .topnav a:hover, .dropdown:hover .dropbtn { background-color: #555; color: white; } /* Add a grey background to dropdown links on hover */ .dropdown-content a:hover { background-color: #ddd; color: black; } /* Show the dropdown menu when the user moves the mouse over the dropdown button */ .dropdown:hover .dropdown-content { display: block; } /* When the screen is less than 600 pixels wide, hide all links, except for the first one ("Home"). Show the link that contains should open and close the topnav (.icon) */ @media screen and (max-width: 600px) { .topnav a:not(:first-child), .dropdown .dropbtn { display: none; } .topnav a.icon { float: right; display: block; } } /* The "responsive" class is added to the topnav with JavaScript when the user clicks on the icon. This class makes the topnav look good on small screens (display the links vertically instead of horizontally) */ @media screen and (max-width: 600px) { .topnav.responsive { position: relative; } .topnav.responsive a.icon { position: absolute; right: 0; top: 0; } .topnav.responsive a { float: none; display: block; text-align: left; } .topnav.responsive .dropdown { float: none; } .topnav.responsive .dropdown-content { position: relative; } .topnav.responsive .dropdown .dropbtn { display: block; width: 100%; text-align: left; } } 

 <button class="dropbtn">Equipment <i class="fa fa-caret-down"></i> </button> <div class="dropdown-content"> <a href="equip.php">Manage equipment</a> <a href="add_equip.php">Add equipment</a> </div> </div> <div class="dropdown"> <button class="dropbtn">Stock <i class="fa fa-caret-down"></i> </button> <div class="dropdown-content"> <a href="Stock.php">Manage stock</a> <a href="add_stock.php">Add stock</a> </div> </div> <div class="dropdown"> <button class="dropbtn">Reports <i class="fa fa-caret-down"></i> </button> <div class="dropdown-content"> <a href="#">Report 1 </a> <a href="#">Report 1 </a> <a href="#">Report 1 </a> </div> </div> <a href="javascript:void(0);" class="icon" onclick="myFunction()">&#9776;</a> </div> <div class="container-fluid"> <div class="row"> <div class="col-md-6"> <?php echo display_msg($msg); ?> </div> </div> <div class="row"> <div class="col-md-3"> <div class="panel panel-box clearfix"> <div class="panel-icon bg-green"> <i class="glyphicon glyphicon-user"></i> </div> <div class="panel-value pull-right"> <h2 class="margin-top"> <?php echo $c_contractors['total']; ?> </h2> <p class="text-muted">Contractors</p> </div> </div> </div> <div class="col-md-3"> <div class="panel panel-box clearfix"> <div class="panel-icon pull-left bg-red"> <i class="glyphicon glyphicon-list"></i> </div> <div class="panel-value pull-right"> <h2 class="margin-top"> <?php echo $c_jobs_active['total']; ?> </h2> <p class="text-muted">Active Jobs</p> </div> </div> </div> <div class="col-md-3"> <div class="panel panel-box clearfix"> <div class="panel-icon pull-left bg-blue"> <i class="glyphicon glyphicon-list"></i> </div> <div class="panel-value pull-right"> <h2 class="margin-top"> <?php echo $c_jobs_pending['total']; ?> </h2> <p class="text-muted">Pending jobs</p> </div> </div> </div> <div class="col-md-3"> <div class="panel panel-box clearfix"> <div class="panel-icon pull-left bg-yellow"> <i class="glyphicon glyphicon-list"></i> </div> <div class="panel-value pull-right"> <h2 class="margin-top"> <?php echo $c_jobs_completed['total']; ?> </h2> <p class="text-muted">Completed Jobs YTD</p> </div> </div> </div> </div> <div class="row"> <div class="col-md-12"> <div class="panel"> <div class="jumbotron text-center"> <h1>Any problems let me know.</h1> </div> </div> </div> </div> </div> 

我敢肯定，我已經看過了一些簡單的事情
干杯，

Answer 1

首先，將.topnav類更改為：

.topnav {
    float:left;
    width:100%;
    position:relative;
    background-color: #333;
}

然后從.dropdown類中消除溢出。 最后，在.dropdown-content類中更改position：相對於position：absolute。

不要忘了添加一個明確的名稱：兩種樣式都在容器流體之前。

這是小提琴 。