i think it is true that
hello
<br>
world
will make the two lines one above the other in the HTML rendering.
and then with
hello
<br><br>
world
and extra black line is added. so let’s say we establish that
rule #1: Two consecutive line-breaks will give an extra blank line
also, is it true that the blank line is taken to be 1em tall, which is line-height?
now however, for the case of
<div>
hello
</div>
<div>
world
</div>
since it is generally true that </div> will generate a line break, and that <div> will always start a line break, so there are two consecutive breaks </div><div> right there, but it doesn’t generate an extra line break, and that would contradict rule #1 above.
I couldn’t find any rule to discuss difference between <br> and <div> in the HTML 4.01 spec. Is it true that they are of different nature of “break”? It may appear that <br> is breaking with inline flow, and break with some empty content, but <div> just means “make sure it starts on new line”, and if it is already on a new line, then don’t worry - don’t break again and just do nothing, as in:
<div>
hello
</div>
<div></div>
<div></div>
<div></div>
<div>
world
</div>
which will show them just one right on top of the other.
since this is related to both design layout and to HTML, I think I will post to both CSS and HTML discussion.