These are getting quite interesting 

Another (some code purposely stripped off in the interest of brevity as it has nothing to do with the actual quiz itself ):

Building on quizzes 1 and 2 (https://www.nairaland.com/nigeria/topic-293811.0.html and https://www.nairaland.com/nigeria/topic-294974.0.html), let's say you have a site with 10 pages and all, thanks to the power of includes, have this code snippet in them:

<style>
div.blah { margin-top: 10px; }
</style>

<div class="blah">blah blah</div>

Now, let's say that 1 or 2 of those pages needs to have a unique top margin.  I could do it in one of 2 ways:

<div class="blah nairaland">blah blah</div> OR <div id="nairaland" class="blah">blah blah</div>

I personally would go for #2 as I don't like "classitis" but for the sake of argument, let's just say I wasn't aware of this "disease" and decided to go for #2 anyways, with the following rule:

<style>
div#nairaland { margin-top: 20px; }
</style>

Questions:
1) Given <div class="blah" id="nairaland">blah blah</div>, which rule (ID or CLASS) gets applied to the particular page
2) why?
3) Which of these is valid syntax?
3a) <div class="blah" class="nairaland">blah blah</div>
3b) <div class="blah nairaland">blah blah</div> OR
3c) <div id="blah nairaland">blah blah</div>
4) Explain your answer to #3 above


As always, I await your answers.

So whats the need of adding class in your DIV?