1div {
2 border: 1px solid #eee;
3}
4div > ul {
5 visibility: hidden;
6 opacity: 0;
7 transition: visibility 0s, opacity 0.5s linear;
8}
9div:hover > ul {
10 visibility: visible;
11 opacity: 1;
12}
13<div>
14 <ul>
15 <li>Item 1</li>
16 <li>Item 2</li>
17 <li>Item 3</li>
18 </ul>
19</div>