W3School TIY Editor

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
#snackbar {
  visibility: hidden;
  min-width: 250px;
  margin-left: -125px;
  background-color: #333;
  color: #fff;
  text-align: center;
  border-radius: 2px;
  padding: 16px;
  position: fixed;
  z-index: 1;
  left: 50%;
  bottom: 30px;
  font-size: 17px;
}

#snackbar.show {
  visibility: visible;
  -webkit-animation: fadein 0.5s, fadeout 0.5s 2.5s;
  animation: fadein 0.5s, fadeout 0.5s 2.5s;
}

@-webkit-keyframes fadein {
  from {bottom: 0; opacity: 0;} 
  to {bottom: 30px; opacity: 1;}
}

@keyframes fadein {
  from {bottom: 0; opacity: 0;}
  to {bottom: 30px; opacity: 1;}
}

@-webkit-keyframes fadeout {
  from {bottom: 30px; opacity: 1;} 
  to {bottom: 0; opacity: 0;}
}

@keyframes fadeout {
  from {bottom: 30px; opacity: 1;}
  to {bottom: 0; opacity: 0;}
}
</style>
</head>
<body>

<h1>底部通知条 / 吐司</h1>

<p>底部通知条常用作工具提示/弹出窗口，可在屏幕底部显示消息。</p>

<p>点击按钮可显示底部通知条。它将在3秒后消失。</p>

<button onclick="myFunction()">显示底部通知条</button>

</body>
</html>