How to build scrollable dropdown menu in Bootstrap v4 when it must hold dozens of choices The Bootstrap dropdown component is very easy to use, but doesn't work so well when it must contain a lot of content. In my case the dropdown contained the Table of Contents for a book with lots of ToC entries, and it didn't even fit well on a large screen. On a small screen for a mobile device, it shrank into unusableness, and Google recently lodged a usability complaint against the site. After researching a ton of alternative designs, a simple solution appeared.