Applied Visual Design: Use CSS Animation to Change the Hover State of a Button

Why are there two curly braces in the same direction, twice in this lesson? Thanks!

Do you have an example or link to the exercise?

You mean this?

@keyframes width {
  100% {
    width: 40px;

The @keyframes is the CSS at-rule, width is the name of the animation and the inner code blocks are the style list of keyframe selectors.

Yes! (lasjorg). Thanks!
Inner code blocks, I see. No mention of inner code blocks in any previous lesson.