When designing a website, a developer uses multiple classes and ID selectors within their stylesheet. They notice that changes to some class styles are not taking effect. What might be the reason based on specificity rules?

Specificity rules in CSS dictate that ID selectors have higher specificity than class selectors. If changes to class styles are not taking effect, it may be because the ID selectors in the stylesheet have higher specificity, causing them to override the class styles. Understanding specificity is essential for resolving styling conflicts.