title: I want to disable background when i click button popup
body: <p>I can't disable background when I open popup, I want hide or make it shadow but I don't know how to add css, please help with my code, I'm a newbie in develop. Thanks for help!</p>
  
  <pre><code>        &lt;div class="searchbox"&gt;
              &lt;form&gt;
                  &lt;input type="text" placeholder="Tìm phòng trọ theo từ khóa" size="25"&gt;
                  &lt;button class="btn" &gt;&lt;i class="fa fa-search"&gt;&lt;/i&gt;&lt;/button&gt;
              &lt;/form&gt;
          &lt;/div&gt;
         &lt;div class="login"&gt;  
               &lt;button type="button" onclick="document.getElementById('loginbox').style.display ='block'"&gt;Đăng nhập ngay&lt;/button&gt;
           &lt;/div&gt;
  
          &lt;div id="loginbox"&gt;
              &lt;img src="images/avatar1.jpg" class="avatar"&gt;
              &lt;h1&gt;Đăng Nhập&lt;/h1&gt;
              &lt;form&gt;
                  &lt;p&gt;Tên đăng nhập&lt;/p&gt;
                  &lt;input type="text" name="" placeholder="Điền tên đăng nhập"&gt;
                  &lt;p&gt;Mật khẩu&lt;/p&gt;
                  &lt;input type="text" name="" placeholder="Mật khẩu"&gt;
                  &lt;input type="submit" name="" value="Đăng nhập"&gt;
                  &lt;a href="Register.html"&gt;Chưa có tài khoản ?&lt;/a&gt;
                  &lt;button onclick="button" onclick="document.getElementById('loginbox').style.display ='none'"&gt;Close&lt;/button&gt;
              &lt;/form&gt;
          &lt;/div&gt;
  </code></pre>
  
  <p>And CSS for this </p>
  
  <pre><code>#loginbox{
    width: 320px;
    height: 420px;
    background-color: white;
    color: #fff;
    top: 45%;
    left: 50%;
    position: absolute;
    transform: translate(-50%,-50%);
    box-sizing: border-box;
    padding: 70px 30px;
    display:none;
  }
  
  body{
    background-image:url(images/background2.png) ;
    -webkit-background-size: cover;
    background-size: cover;
    background-position: center center;
    height: 100vh;        
  }
  </code></pre>