[docs beta] "Scrolling to an element" example does not work on Safari

Checking the beta docs, I noticed that one of the examples was not working. At first it was not working at all, but after I added a style of overflow-x: auto to the <ul> element, then I could see the desired effect after clicking on the buttons. I could later check that the example works as expected (without any changes in Chrome). My first guess is that Safari doesn't scroll because the element has an implicit overflow as visible.

Please note that this issue is also present on the challenge 3, as it basically uses that same principle to scroll the images.

Steps

1. Open https://beta.reactjs.org/learn/manipulating-the-dom-with-refs#example-scrolling-to-an-element on Safari
2. Click on the buttons

首先在 Safari 中复现 React beta 文档“Scrolling to an element”部分的示例，然后将其与使用相同滚动原理的 challenge 3 进行比较。调查报告的 overflow 行为，并验证点击两个示例中的按钮时，它们都能按预期工作，且无需手动更改样式。