Why Does My `.foo a:link` and `.foo a:visited` CSS Override `a:hover` and `a:active`?

Why Does .foo a:link, .foo a:visited Selector Override a:hover, a:active Selector in CSS?

The unexpected behavior described in the question arises from the specificity rules of CSS. Specificity determines the precedence of CSS rules when multiple rules apply to the same element.

Specificity Table:

Selector	Specificity
a:link	0-0-1-1
a:visited	0-0-1-1
a:hover	0-0-1-1
a:active	0-0-1-1
.foo a:link	0-0-2-1
.foo a:visited	0-0-2-1

As you can see, .foo a:link and .foo a:visited have slightly higher specificity than a:hover and a:active due to the additional class selector .foo.

How Specificity Override Works:

When multiple rules with different specificities apply to the same element, the rule with the higher specificity takes precedence. In this case, .foo a:link and .foo a:visited have higher specificity than a:hover and a:active, so their styles override those of the latter.

Correcting the Behavior:

To prevent the .foo a:link, .foo a:visited selector from overriding a:hover, a:active, you can increase the specificity of the latter. This can be achieved by adding a child selector to the hover/active rules:

.foo a:hover, .foo a:active {
  color: red;
}

By adding the .foo class as a child selector, the specificity of the hover/active rules increases to 0-0-3-1, which is higher than that of .foo a:link and .foo a:visited. As a result, the hover/active styles will have precedence and take effect over the link/visited styles when both pseudo-classes are applicable.

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