CSS3 selector :first-of-type with class name?

Question

Is it possible to use the CSS3 selector :first-of-type to select the first element with a given class name? I haven't been successful with my test so I'm thinking it's not?

The Code (http://jsfiddle.net/YWY4L/):

p:first-of-type {color:blue}
p.myclass1:first-of-type {color:red}
.myclass2:first-of-type {color:green}

<div>
  <div>This text should appear as normal</div>
  <p>This text should be blue.</p>
  <p class="myclass1">This text should appear red.</p>
  <p class="myclass2">This text should appear green.</p>
</div>

Answer 1

The draft CSS Selectors Level 4 proposes to add an of <other-selector> grammar within the :nth-child selector. This would allow you to pick out the nth child matching a given other selector:

:nth-child(1 of p.myclass) 

Previous drafts used a new pseudo-class, :nth-match(), so you may see that syntax in some discussions of the feature:

:nth-match(1 of p.myclass)

This has now been implemented in WebKit, and is thus available in Safari, but that appears to be the only browser that supports it. There are tickets filed for implementing it Blink (Chrome), Gecko (Firefox), and a request to implement it in Edge, but no apparent progress on any of these.

Answer 2

No, it's not possible using just one selector. The :first-of-type pseudo-class selects the first element of its type (div, p, etc). Using a class selector (or a type selector) with that pseudo-class means to select an element if it has the given class (or is of the given type) and is the first of its type among its siblings.

Unfortunately, CSS doesn't provide a :first-of-class selector that only chooses the first occurrence of a class. As a workaround, you can use something like this:

.myclass1 { color: red; }
.myclass1 ~ .myclass1 { color: /* default, or inherited from parent div */; }

Explanations and illustrations for the workaround are given here and here.