Differences in styling elements

I am curious about the differences between the following two methods for styling an element like an unordered list

Method 1.
#div_name ul {}

Method 2.
ul.div_name {}


as far as i know, “.” is to define a class, “#” is to define an ID

Method 1 works for a <ul> that is inside some other element with id=“div_name”.

Method 2 works for <ul class=“div_name”>

Haha, which should make Method 2

<ul class=“ul_class_name”> and

ul.ul_class_name {}

There’s also
ul#div_name {} which would select for a <ul id=“div_name”>

it’s a little more involved that that, but only a little.

#div_name ul {}
would target a child of the id “div_name”
so it would look like this:

<div id=“div_name”>
<ul>… </ul>

Method 2.
ul.div_name {}
would target ONLY ULs that have the CLASS “div_name”

<ul>…</ul> <!-- would not be targeted–>
<ul class=“x”>…</ul> <!-- would not be targeted–>
<DIV class=“div_name”>…</ul> <!-- would not be targeted–>
<ul class=“div_name”>…</ul> <!-- would be targeted–>

in the example above, if you have merely used .div_name{} then you your rules would have applied to the div as well ( along with any other tags that had the class “div_name”).

you could have this as well, ul#div_name{} and the same principle as above would apply… only to classes instead of divs. It works and it is totally val;id, but leaves the question of WHY??? as an ID is unique on a page so you SHOULDN’T have to be worrying that you may have a <div id=“div_name”> and a <UL id=“div_name”>. so the occasions in which it would make sense to have something like ul#div_name{} are quite rare.

I was assuming that div_name was just a generic name the OP gave, and not actually the name given to a div.

Off Topic:

Btw, dresden_phoenix, jim butcher fan?