[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

Commencez par reproduire dans Safari l’exemple de la section « Scrolling to an element » de la documentation bêta de React, puis comparez-le avec challenge 3, qui utilise le même principe de défilement. Examinez le comportement d’overflow signalé et vérifiez que les deux exemples fonctionnent comme prévu lorsque vous cliquez sur leurs boutons, sans modifier manuellement les styles.