提升网页设计专业水平，学习常用CSS框架

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">网站名称</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarNav">
    <ul class="navbar-nav">
      <li class="nav-item active">
        <a class="nav-link" href="#">首页</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">产品</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">关于我们</a>
      </li>
    </ul>
  </div>
</nav>

<button class="button">点击这里</button>

<form>
  <div class="field">
    <label class="label">用户名</label>
    <div class="control">
      <input class="input" type="text" placeholder="请输入用户名">
    </div>
  </div>
  <div class="field">
    <label class="label">密码</label>
    <div class="control">
      <input class="input" type="password" placeholder="请输入密码">
    </div>
  </div>
  <div class="field">
    <div class="control">
      <button class="button is-primary">登录</button>
    </div>
  </div>
</form>

<div class="ui card">
  <div class="image">
    <img src="image.jpg">
  </div>
  <div class="content">
    <div class="header">卡片标题</div>
    <div class="meta">发布于今天</div>
    <div class="description">这是卡片的描述内容。</div>
  </div>
  <div class="extra content">
    <span class="right floated">
      <i class="heart outline icon"></i>
      喜欢
    </span>
    <span>
      <i class="comment icon"></i>
      评论
    </span>
  </div>
</div>