navbar更改滾動時，實現css

Question

我試圖複製類似於此website的導航欄。所以當用戶打開網站時有一個非粘性的導航欄，並且在用戶向下滾動一點之後，不粘的導航欄消失了，並被一個粘滯的導航欄取代。我如何用物化css達到這樣的效果？到目前爲止，我只取得了不粘性導航欄部分

<nav class="nav-extended"> 
    <div class="nav-wrapper"> 
     <a href="#" class="brand-logo"><img src="viva.png" alt="" id="logo"></a> 
     <ul id="nav-mobile" class="right hide-on-med-and-down"> 
      <li> 
       <form> 
        <div class="input-field"> 
         <input id="search" type="search" required> 
         <label class="label-icon" for="search"><i class="material-icons"></i></label> 
         <i class="material-icons">close</i> 
        </div> 
       </form> 
      </li> 
      <li><a href="#">Register</a></li> 
      <li>|</li> 
      <li><a href="#">Login</a></li> 
     </ul> 
    </div> 
    <hr> 
    <div class="nav-content"> 
     <ul class="tabs tabs-transparent"> 
      <li class="tab"><a href="#">Test 1</a></li> 
      <li class="tab"><a href="#">Test 2</a></li> 
      <li class="tab"><a href="#">Test 3</a></li> 
     </ul> 
    </div> 
</nav> 

Answer 1

試試這個：

HTML

<div class="header">Header Example</div> 
<div class="content"> 
<p> 
Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur. 
</p> 
</div> 

CSS

body { 
    margin:0; 
    padding:0; 
    font-family: Arial, sans-serif; 
} 

header { 
    position: relative; 
    width: 100%; 
    height: 80px; 
    line-height: 80px; 
    background: #CCCCCC; 
    color: #333333; 
    padding-left: 25px; 
} 
header.fixed { 
    position:fixed; 
    top:-80px; 
    left: 0; 
    right: 0; 
    z-index:8888; 
    transition:0.3s top cubic-bezier(.3,.73,.3,.74); 
} 
body.on-scroll header.fixed { 
    top:0; 
} 
.content { 
    padding: 25px; 
    background: #fff; 
    line-height: 1.4; 
    color: #333; 
    min-height: 2700px; /* You can remove this,is just for demo purpose */ 
} 

的jQuery：

(function($){ 
    $(document).ready(function() { 
     var $header = $(".header"), 
      $clone = $header.before($header.clone().addClass("fixed")); 

     $(window).on("scroll", function() { 
      var fromTop = $(window).scrollTop(); 
      $("body").toggleClass("on-scroll", (fromTop > 200)); 
     }); 
    }); 
})(jQuery); 

這裏是一個jsfiddle的例子。