Where do I add HTML with SVG?

I'd like to know where do I add HTML with SVG in Contao.

The code is this:

<div class="artwork">
<svg viewBox="0 0 3387 1270">
<path id="planePath" class="planePath" d="M-226 626c439,4 636,-213 934,-225 755,-31 602,769 1334,658 562,-86 668,-698 266,-908 -401,-210 -893,189 -632,630 260,441 747,121 1051,91 360,-36 889,179 889,179"/>

<g id="plane">
<polygon class="fil1" points="-141,-10 199,0 -198,-72 -188,-61 -171,-57 -184,-57 "/>
<polygon class="fil2" points="199,0 -141,-10 -163,63 -123,9 "/>
<polygon class="fil3" points="-95,39 -113,32 -123,9 -163,63 -105,53 -108,45 -87,48 -90,45 -103,41 -94,41 "/>
<path class="fil4" d="M-87 48l-21 -3 3 8 19 -4 -1 -1zm-26 -16l18 7 -2 -1 32 -7 -29 1 11 -4 -24 -1 -16 -18 10 23zm10 9l13 4 -4 -4 -9 0z"/>
<polygon class="fil1" points="-83,28 -94,32 -65,31 -97,38 -86,49 -67,70 199,0 -123,9 -107,27 "/>
</g>
<!-- Define the motion path animation -->
<animateMotion
xlink:href="#plane"
dur="5s"
repeatCount="indefinite"
rotate="auto">
<mpath xlink:href="#planePath" />
</animateMotion>
</svg>
</div>

I've added the code in a HTML content element in Contao, but doesn't show, not even in the internal editor once I saved it - only the comment remains.

I also tried adding it as a module, but the result is the same.

The code works in my external code editor and in code pen. It's this: http://codepen.io/CarolinaSawney/pen/gaqVpd

By the way, I'm using Contao 3.4 that supports SVG.

Thanks!