W3School TIY Editor

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
* {box-sizing: border-box;}

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

#navbar {
  overflow: hidden;
  background-color: #f1f1f1;
  padding: 90px 10px;
  transition: 0.4s;
  position: fixed;
  width: 100%;
  top: 0;
  z-index: 99;
}

#navbar a {
  float: left;
  color: black;
  text-align: center;
  padding: 12px;
  text-decoration: none;
  font-size: 18px; 
  line-height: 25px;
  border-radius: 4px;
}

#navbar #logo {
  font-size: 35px;
  font-weight: bold;
  transition: 0.4s;
}

#navbar a:hover {
  background-color: #ddd;
  color: black;
}

#navbar a.active {
  background-color: dodgerblue;
  color: white;
}

#navbar-right {
  float: right;
}

@media screen and (max-width: 580px) {
  #navbar {
    padding: 20px 10px !important;
  }
  #navbar a {
    float: none;
    display: block;
    text-align: left;
  }
  #navbar-right {
    float: none;
  }
}
</style>
</head>
<body>

<div id="navbar">
  <a href="#default" id="logo">CompanyLogo</a>
  <div id="navbar-right">
    <a class="active" href="#home">Home</a>
    <a href="#contact">Contact</a>
    <a href="#about">About</a>
  </div>
</div>

<div style="margin-top:210px;padding:15px 15px 2500px;font-size:30px">
  <p><b>此例展示了当用户开始滚动页面时，如何缩小导航栏。</b></p>
  <p>向下滚动此框架可查看效果！</p>
  <p>滚动到顶部可取消该效果。</p>
  <p><b>注意：</b>我们还使导航栏具有响应性，调整浏览器窗口大小可查看效果。</p>
  <p>Lorem ipsum dolor dummy text to enable scrolling, sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
</div>

</body>
</html>