console 命令行工具 X clear
console
<!DOCTYPE html>
<html>

<head>
	<meta charset="utf-8">
	<title>菜鸟教程(runoob.com)</title>
</head>
<style>
	.exptip {
		position: relative;
		display: inline-block;
		/* border-bottom: 1px dotted black; */
	}

	.exptip .exptiptext {
		visibility: hidden;
		width: 120px;
		background-color: black;
		color: #fff;
		font-size: 12px;
		text-align: left;
		border-radius: 6px;
		padding: 5px 0;
		padding-left: 8px;
		position: absolute;
		z-index: 1;
		top: 150%;
		left: 50%;
		margin-left: -60px;
		/* 淡入 - 1秒内从 0% 到 100% 显示: */
		opacity: 0;
		transition: opacity 1s;
	}

	.exptip .exptiptext::after {
		content: "";
		position: absolute;
		bottom: 100%;
		left: 50%;
		margin-left: -5px;
		border-width: 5px;
		border-style: solid;
		border-color: transparent transparent black transparent;
	}

	.exptip:hover .exptiptext {
		visibility: visible;
		opacity: 1;
	}
</style>

<body style="text-align:center;">

	<h2>底部提示框/顶部箭头</h2>

	<div class="exptip">参考（https://www.runoob.com/css/css-tooltip.html）
		<span class="exptiptext">
	价格：当日价格；<br>
                                价差：环比价差；<br>
                                其中左侧数据为价格，右侧为涨跌值；</span>
</div>

</body>
</html>