Thank you for replying!
Well... the empty <div> does something, but still there's a gremlin somewhere
(sorry for the bold font... using it to highlight comments)
For the question in Spanish, I first entered:
<script type="text/javascript" charset="utf-8">
alert ("Hello world");
</script>
When I re-opened the source code, I got:
<br />
<script type="text/javascript" charset="utf-8">
alert ("Hello world");
</script>
So... now I entered the empty <div>:
<div></div>
<script type="text/javascript" charset="utf-8">
alert ("Hello world");
</script>
...and upon re-opening the source code, I get:
<div>
</div>
<script type="text/javascript" charset="utf-8">
alert ("Hello world");
</script>
I guess I can modify the 1st language so it looks like the 2nd one after the gremlin-induced </br>, but the question is: why do this thing appear *only* on the 2nd language?