我不知道为什么"行高"在 iframe 下失去效力，以前有人遇到过同样的问题吗？顺便说一下，有两个区别： 1.我以某种方式使用了iframe：document.write不是src。有关系吗？ 2.div 下有一个svg 标签
<div style="line-height: 20;">
<i aria-label="icon: warning" class="anticon anticon-warning icon" style="font-size: 22px;">
<svg viewBox="64 64 896 896" focusable="false" class="" data-icon="warning" width="1em" height="1em" fill="currentColor" aria-hidden="true"><path d="M464 720a48 48 0 1 0 96 0 48 48 0 1 0-96 0zm16-304v184c0 4.4 3.6 8 8 8h48c4.4 0 8-3.6 8-8V416c0-4.4-3.6-8-8-8h-48c-4.4 0-8 3.6-8 8zm475.7 440l-416-720c-6.2-10.7-16.9-16-27.7-16s-21.6 5.3-27.7 16l-416 720C56 877.4 71.4 904 96 904h832c24.6 0 40-26.6 27.7-48zm-783.5-27.9L512 239.9l339.8 588.2H172.2z"></path>
</svg>
</i>
</div>
下面是一个完整的示例：
setTimeout(function() {
var iframe = document.getElementById('iframe');
var doc = iframe.contentWindow.document;
var body = iframe.contentWindow.document.body;
doc.open();
doc.write(`
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>EDITOR DEMO IFRAME</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/antd@3.26.8/dist/antd.min.css" />
</head>
<body>
test
<div style="line-height: 20;">
<i aria-label="icon: warning" class="anticon anticon-warning icon" style="font-size: 22px;"><svg viewBox="64 64 896 896" focusable="false" class="" data-icon="warning" width="1em" height="1em" fill="currentColor" aria-hidden="true"><path d="M464 720a48 48 0 1 0 96 0 48 48 0 1 0-96 0zm16-304v184c0 4.4 3.6 8 8 8h48c4.4 0 8-3.6 8-8V416c0-4.4-3.6-8-8-8h-48c-4.4 0-8 3.6-8 8zm475.7 440l-416-720c-6.2-10.7-16.9-16-27.7-16s-21.6 5.3-27.7 16l-416 720C56 877.4 71.4 904 96 904h832c24.6 0 40-26.6 27.7-48zm-783.5-27.9L512 239.9l339.8 588.2H172.2z"></path></svg></i>
</div>
</body>
`);
doc.close();
}, 2000)<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>EDITOR DEMO</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/antd@3.26.8/dist/antd.min.css" />
</head>
<body>
<div id="app">
<div>
<i aria-label="icon: warning" class="anticon anticon-warning icon" style="font-size: 22px;"><svg viewBox="64 64 896 896" focusable="false" class="" data-icon="warning" width="1em" height="1em" fill="currentColor" aria-hidden="true"><path d="M464 720a48 48 0 1 0 96 0 48 48 0 1 0-96 0zm16-304v184c0 4.4 3.6 8 8 8h48c4.4 0 8-3.6 8-8V416c0-4.4-3.6-8-8-8h-48c-4.4 0-8 3.6-8 8zm475.7 440l-416-720c-6.2-10.7-16.9-16-27.7-16s-21.6 5.3-27.7 16l-416 720C56 877.4 71.4 904 96 904h832c24.6 0 40-26.6 27.7-48zm-783.5-27.9L512 239.9l339.8 588.2H172.2z"></path></svg></i>
</div>
iframe：
<iframe id="iframe" style="width: 500px; height: 500px; border: 1px solid #ccc;"></iframe>
</div>
</body>
</html>解决了！ 运行doc.write时缺少<!DOCTYPE html>和<html>。
setTimeout(function() {
var iframe = document.getElementById('iframe');
var doc = iframe.contentWindow.document;
var body = iframe.contentWindow.document.body;
doc.open();
doc.write(`
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>EDITOR DEMO IFRAME</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/antd@3.26.8/dist/antd.min.css" />
</head>
<body>
test
<div style="line-height: 20;">
<i aria-label="icon: warning" class="anticon anticon-warning icon" style="font-size: 22px;"><svg viewBox="64 64 896 896" focusable="false" class="" data-icon="warning" width="1em" height="1em" fill="currentColor" aria-hidden="true"><path d="M464 720a48 48 0 1 0 96 0 48 48 0 1 0-96 0zm16-304v184c0 4.4 3.6 8 8 8h48c4.4 0 8-3.6 8-8V416c0-4.4-3.6-8-8-8h-48c-4.4 0-8 3.6-8 8zm475.7 440l-416-720c-6.2-10.7-16.9-16-27.7-16s-21.6 5.3-27.7 16l-416 720C56 877.4 71.4 904 96 904h832c24.6 0 40-26.6 27.7-48zm-783.5-27.9L512 239.9l339.8 588.2H172.2z"></path></svg></i>
</div>
</body>
</html>
`);
doc.close();
}, 2000)