CSS Transitions:
https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Transitions/Using_CSS_transitions
CSS Animations:
https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Animations/Using_CSS_animations
List of "transitionable" Properties:
https://www.w3.org/TR/css-transitions-1/#animatable-properties