使用：first-line元素可在文档的第一行元素中添加特殊效果。
您可以尝试运行以下代码以在文本的第一行中添加特殊样式
<html>
<head>
<style>
p:first-line {
text-decoration: underline;
}
p.noline:first-line {
text-decoration: none;
}
</style>
</head>
<body>
<p class = "noline"> This line would not have any underline because this belongs to nline class.</p>
<p>The first line of this paragraph will be underlined as defined in the CSS rule above. Rest of the
lines in this paragraph will remain normal. This example shows how to use :first-line pseduo element
to give effect to the first line of any HTML element.</p>
</body>
</html>