Right ToC doesn't render on the first load

Seems like on Chrom(e|ium), when you load a page, the first time the ToC doesn't move on the right. It happens on a refresh.

Seems !368 (merged) causes this.

Examples:

• https://docs.gitlab.com/ee/user/project/settings/
• https://docs.gitlab.com/ee/user/project/web_ide/
• https://docs.gitlab.com/ee/