<!--[if IE]><style>
.layout {
    height: 0;
    he\ight: auto;
    zoom: 1;
}
</style><![endif]-->

Tell IE to use standards mode, not quirks mode

Define your doctype in your HTML:

<!DOCTYPE> element

See: https://msdn.microsoft.com/en-us/library/cc288325(v=vs.85).aspx

Tell IE to not use compatibility mode

This prevents, for example, IE 11 from using IE 7 rendering mode which can happen for many reasons.

If you can’t add an HTTP header, then add this to your HTML and pray that it helps:

<meta http-equiv="X-UA-Compatible" content="IE=edge" />

IE is using a compatibility mode if you see “compatible; MSIE” in the user agent header:

"Mozilla/4.0 (compatible; MSIE 7.0;"

See:

• http://stackoverflow.com/a/9338959
• https://msdn.microsoft.com/en-us/library/ff405803(v=vs.85).aspx
• https://blogs.msdn.microsoft.com/ieinternals/2013/09/21/internet-explorer-11s-many-user-agent-strings/

Validate your HTML and CSS

https://validator.w3.org/

Use an IE hack

Try “zoom” or “!important”.