CSS argument for “if first child is”

问题:

I need a CSS selector for inside a div but I want it to only select the element if its the first element of a specific class inside that div.

回答1:

As your title implies "if first child is": div > .test:first-child will select the first child of any <div> if it has the class test.

But if the first child of the <div> doesn't have the class test, then it won't continue searching the <div> until it finds a child with the class test — it just won't match anything. I'm not sure if that's what you want.