Rollup merge of rust-lang#85289 - GuillaumeGomez:fix-toggle-position-…

…mobile, r=jsha

Fix toggle position on mobile

Before:

![Screenshot from 2021-05-14 14-21-27](https://user-images.githubusercontent.com/3050060/118276475-fe210300-b4c7-11eb-94f8-4e2a4e10d91e.png)
![Screenshot from 2021-05-14 14-21-30](https://user-images.githubusercontent.com/3050060/118276479-feb99980-b4c7-11eb-85db-40e9df6e9abd.png)

After:

![Screenshot from 2021-05-14 15-16-54](https://user-images.githubusercontent.com/3050060/118276494-0416e400-b4c8-11eb-9479-d447928cfa62.png)
![Screenshot from 2021-05-14 15-16-59](https://user-images.githubusercontent.com/3050060/118276498-0416e400-b4c8-11eb-99f6-894276c62dfc.png)

r? ``@jsha``