How do I select an element that has a certain class? - html

Question

My understanding is that using element.class should allow for a specific element assigned to a class to receive different "styling" than the rest of the class. This is not a question about whether this should be used or not, but rather I'm trying to understand how this selector is intended to work. From looking at a ton of examples on the internet, I believe the syntax is correct and do not understand why this is not working.
Here is an example:
CSS:
h2 {
color: red;
}
.myClass {
color: green;
}
h2.myClass {
color: blue;
}
HTML:
<h2>This header should be RED to match the h2 element selector</h2>
<div class="myClass">
<h1>This header should be GREEN to match the class selector</h1>
<h2>This header should be BLUE to match the element.class selector</h2>
</div>

Answer 1

It should be this way:
h2.myClass looks for h2 with class myClass. But you actually want to apply style for h2 inside .myClass so you can use descendant selector .myClass h2.
h2 {
color: red;
}
.myClass {
color: green;
}
.myClass h2 {
color: blue;
}
Demo
This ref will give you some basic idea about the selectors and have a look at descendant selectors

Answer 2

h2.myClass refers to all h2 with class="myClass".
.myClass h2 refers to all h2 that are children of (i.e. nested in) elements with class="myClass".
If you want the h2 in your HTML to appear blue, change the CSS to the following:
.myClass h2 {
color: blue;
}
If you want to be able to reference that h2 by a class rather than its tag, you should leave the CSS as it is and give the h2 a class in the HTML:
<h2 class="myClass">This header should be BLUE to match the element.class selector</h2>

Answer 3

The element.class selector is for styling situations such as this:
<span class="large"> </span>
<p class="large"> </p>
.large {
font-size:150%; font-weight:bold;
}
p.large {
color:blue;
}
Both your span and p will be assigned the font-size and font-weight from .large, but the color blue will only be assigned to p.
As others have pointed out, what you're working with is descendant selectors.

Answer 4

h2.myClass is only valid for h2 elements which got the class myClass directly assigned.
Your want to note it like this:
.myClass h2
Which selects all children of myClass which have the tagname h2

Answer 5

The CSS :first-child selector allows you to target an element that is the first child element within its parent.
element:first-child { style_properties }
table:first-child { style_properties }