Fix having to double click number to select in introduction page

Status Job ID Name Coverage
  Codestyle
passed #171196
nodejs
tslint

00:01:47

 
  Test
passed #171197
nodejs
unit_tests

00:01:46

 
  Build
failed #171198
angular
ngbuild

00:02:01

 
  Review
skipped #171199
nginx
review
skipped #171200
nginx allowed to fail manual
stop_review
 
Name Stage Failure
failed
ngbuild Build
"): /builds/arsnova/frag.jetzt/src/assets/i18n/demo/demo-en.html@49:0
Unexpected closing tag "h3". It may happen when the tag has already been closed by another tag. For more info see https://www.w3.org/TR/html5/syntax.html#closing-elements-that-have-implied-end-tags ("
<div id="demoContent" tabindex="3">
»Do you have any questions?«
[ERROR ->]</h3>

<p>The classical lecture usually ends with: »Do you have any questions?« And always nobody a"): /builds/arsnova/frag.jetzt/src/assets/i18n/demo/demo-en.html@52:0

ERROR: Job failed: exit code 1