introduce bootstrap 4

important clarification: this is not for upgrading bootstrap 3. This is to introduce new and useful features from bootstrap 4 that we don't currently have, and would benefit from. These can exist alongside our existing bootstrap 3 imports without conflicts (they are different/new classnames).

bootstrap 4 introduces a sensible reboot, and some extremely useful util classes/mixins.

A lot of this can be added alongside existing styles without conflicts. For example we can add https://github.com/twbs/bootstrap/blob/v4-dev/scss/_utilities.scss - then add/upgrade components as needed.

Some core parts and breaking changes (e.g grids) would be a larger effort.

Should attempt https://gitlab.com/gitlab-org/gitlab-ce/issues/38330 first,

Migration guide/breaking changes: https://getbootstrap.com/docs/4.0/migration/
Migration tool: http://upgrade-bootstrap.bootply.com/

Edited Oct 14, 2017 by Simon Knox