HTML CSS composes, and pseudo-element :after, :active:after, and transition

# HTML CSS composes, and pseudo-element :after, :active:after, and transition Buttons Images ## Style ```[#pre-code-style-transition.linenums.lang-css] ```/ composes 는 module 단에서만 동작하는듯. ## HTML ```[.linenums.lang-html] Buttons <button class="button0">Add Amount</button> <button class="button0 asyncButton">Add Async</button> <button class="button0">Add If Odd</button> Images <img class="img-transition" src="https://i.imgur.com/r3RMdYs.gif" /> ```/ ## RRA

1. https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_transitions/Using_CSS_transitions
2. https://poiemaweb.com/css3-transition