How to force quirks mode in IE7 (while keeping to standards mode in IE8+)
If you put an HTML comment above the doctype declaration, it causes IE7 to enter quirks mode, but not any other browsers.
<!-- This forces quirks mode in IE7 only -->
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=Edge">
<title>Quirks mode in IE7!</title>
</head>
<body></body>
</html>