Bootstrap实现渐变顶部固定自适应导航栏

具体代码如下所示:

<!DOCTYPE html> 
<html> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> 
 <title></title> 
 <meta charset="utf-8" />
 <link href="<%=path%>/css/style.css" rel="stylesheet" type="text/css" /> 
 <link rel="stylesheet" href="http://cdn.static.runoob.com/libs/bootstrap/3.3.7/css/bootstrap.min.css"> 
 <script src="http://cdn.static.runoob.com/libs/jquery/2.1.1/jquery.min.js"></script> 
 <script src="http://cdn.static.runoob.com/libs/bootstrap/3.3.7/js/bootstrap.min.js"></script> 
</head> 
<body> 
 <nav class="navbar navbar-fixed-top my-navbar" role="navigation"> 
  <div class="container-fluid"> 
   <div class="navbar-header"> 
    <button type="button" class="navbar-toggle" data-toggle="collapse" 
      data-target="#example-navbar-collapse"> 
     <span class="sr-only">切换导航</span> 
     <span class="icon-bar"></span> 
     <span class="icon-bar"></span> 
     <span class="icon-bar"></span> 
    </button> 
    <a class="navbar-brand" href="#">菜鸟教程</a> 
   </div> 
   <div class="collapse navbar-collapse" id="example-navbar-collapse"> 
    <ul class="nav navbar-nav"> 
     <li class="active"><a href="#">iOS</a></li> 
     <li><a href="#">SVN</a></li> 
     <li><a href="#">Asp.Net</a></li> 
    </ul> 
   </div> 
  </div> 
 </nav> 
  <div class="bg"></div> 
 <script> 
  $(window).scroll(function () { 
   if ($(".navbar").offset().top > 50) {$(".navbar-fixed-top").addClass("top-nav"); 
   }else {$(".navbar-fixed-top").removeClass("top-nav");} 
  })</script> 
</body></html>

style.css

html, body {width:100%;height:100%;} /*非常重要的样式让背景图片100%适应整个屏幕*/ 
  .bg {display: table;width: 100%;height: 100%;padding: 100px 0;text-align: center;color: #fff;background: url(http://www.xiandanke.cn/Image/intro-bg.jpg) no-repeat bottom center;background-color: #000;background-size: cover;} 
  .my-navbar {padding:20px 0;transition: background 0.5s ease-in-out, padding 0.5s ease-in-out;} 
  .my-navbar a{background:transparent !important;color:#fff !important} 
  .my-navbar a:hover {color:#45bcf9 !important;background:transparent;outline:0} 
  .my-navbar a {transition: color 0.5s ease-in-out;}/*-webkit-transition ;-moz-transition*/ 
  .top-nav {padding:0;background:#000;} 
  button.navbar-toggle {background-color:#fbfbfb;}/*整个背景都是transparent透明的,会看不到,所以再次覆盖一下*/ 
  button.navbar-toggle > span.icon-bar {background-color:#dedede}

真的只用了9行代码,原理挺简单的,但是要注意以下几点

1.html,body{width:100%;height:100%} ,必须写这个样式,才能让html中的子元素100%占满整个屏幕,也就是要实现背景图片占满100%的整个屏幕

2.bootstrap中的类 nav-fixed-top的意义在于固定导航栏在顶部

3.添加scroll 事件,在切换class的时候实现动态的效果

4.整个效果的实现原理是使用了transition 属性,transition属性的使用方法是:

Bootstrap实现渐变顶部固定自适应导航栏

相关推荐