[TYPO3] Typo3 3.7.1 and RTE

[tapio]

Hi

One old customer has
Typo3 3.7.1.

I didn't figure how to get it render properly h1, h2 etc.
it turned them into

<p style="margin:0 0 0 0;">&lt;h1&gt;Heading1&lt;/h1&gt;
</p>