odin-default-css-exercises/animation/02-drop-down/solution/solution.css

* {
  padding: 0;
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
}

.dropdown-container {
  width: 100vw;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

.dropdown-menu {
  position: relative;
}

button {
  background-color: rgb(108, 238, 255);
  padding: 16px;
  font-size: 16px;
  border: none;
}

ul {
  position: absolute;
  left: -25%;
  background-color: rgb(189, 188, 188);
  width: 160px;
  list-style: none;
  text-align: center;
}

li {
  padding: 16px;
}

/* SOLUTION */

/* disclaimer: duplicating the `ul` element here isn't best practice.
In your solution you probably put it right inside the existing `ul`,
which _is_ the best practice. 
We separated it out here to make it extra clear what has changed. */

ul {
  overflow: hidden;
  max-height: 0;
  transition: max-height 0.25s ease-out;
}

.dropdown-menu:hover ul {
  max-height: 500px;
  transition: max-height 0.5s ease-out;
}

button:hover {
  cursor: pointer;
  background-color: rgb(59, 232, 255);
}

ul li:hover {
  cursor: pointer;
  background-color: #ddd;
}