cascading style sheets the definitive guide class ations Applying or removing classes triggers CSS transitions or keyframe animations. ```css .fade-in { opacity: 0; transition: opacity 0.5s ease-in; } .fade-in.show { opacity: 1; } ``` ```javascript element.classList.add('show'); ``` Features: Smooth visual effects Enhances engagement Pros: Keeps R Rosie Buckridge Apr 5, 2026
