问题：

Safari renders the text in blue, while Chrome and Firefox use red.

Cause:

The root cause is Safari's recent implementation of the level 4 :not() selector, which allows complex selectors as arguments. Chrome and Firefox, on the other hand, only support single-level arguments in the current version of :not().

Explanation:

A complex selector includes multiple compound selectors separated by combinators (e.g., descendant, sibling).在这种情况下，“ p div”是一个复杂的选择器，由两个化合物选择器（“ p”和“ div”）组成，由后代组合分隔。

em:not(div) {
    color: red
}
em:not(p div) {
    color: blue
}

很少，这会导致Chrome and Firefox和Firefox最终最终达到一致，从而导致浏览器跨浏览器的一致行为。在此之前，开发人员在使用以下情况时应了解潜在的差异：NOT（）选择器在这些浏览器中具有多个级别。