我搜索并搜索试图找出我的代码有什么问题。我想在某个屏幕宽度上完全隐藏导航栏，但我什么也没得到。JS fiddle 和 Code Pen 找不到任何东西，safari 也没有显示语法错误。我只在这里待了一个月，在这里我感谢任何帮助。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>No clue what I am doing</title>
<link href="css/bootstrap.min.css" rel="stylesheet"/>
<link href="stylesheet.css" rel="stylesheet" type="text/css" />
</head>
<body>
<nav class="navbar-default">
<div class="container-fluid">
<!-- Brand and toggle get grouped for better mobile display -->
<div class="navbar-header">
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
</div>
<!-- Collect the nav links, forms, and other content …