How to use :not and :first-child pseudo selectors simultaneously

Question

I want to select the first li without class="test" using :not and :first-child pseudoclasses. In this example I try to set color blue to <li>Third</li>:

ul li {
    color:red;
}

ul li:not(.test):first-child {
    color:blue;
}

<ul>
    <li class="test">First</li>
    <li class="test">Second</li>
    <li>Third</li>
    <li>Fourth</li>
</ul>

Answer 1

Why not do the below, which uses a combination of rules to filter the item you need (you can combine rules #1 and #3).

This has the added advantage of it not mattering what the index is of the first item with the class .test

ul li { /* <-- select all list items */
  color: red;
}
li:not(.test) { /* <-- select all list which arent test */
  color: blue;
}
ul li:not(.test) ~ li { /* <-- select all list items which follow an item without test */
  color: red;
}

<ul>
  <li class="test">First</li>
  <li class="test">Second</li>
  <li>Third</li>
  <li>Fourth</li>
</ul>