When you are trying to highlight some code that contains special characters, this can mess up your markup. So you need to escape some characters first, for example replace all < and > with &lt; and &gt;. I used this page to find the codes.

I’ve had enough of copy-paste-replace-this-replace-that-copy-paste, so I created a page of my own that does at least replacing part:

Escape your HTML for highlighting

The core of the replacing mechanism is this RegEx:

<[^>]*>|{{[^%]*}}|{%[^%]*%}|{.*}

It can also re-escape the result, sometimes it can eventually escape unescaped. You can do it by pressing the button with the ← in the middle.

You can see, that it escapes only pretty basic stuff, so don’t rely on it in any somewhat difficult cases.