Currently I'm using Ember Bootstrap Tooltip component, I read the doc, I didn't found anything about custom Background-color. It will be helpful if someone show me how to do it.
This question has been answered by Simon Ihmig one of the maintainers of Ember Bootstrap in a GitHub issue.
You don't apply any styling via JS, you customize the BS components as you would for any other Bootstrap-based project. If using plain CSS (not recommended), you would need to override the default styles using CSS, If using Sass (recommended!), you can just tweak the related Sass variables. See https://getbootstrap.com/docs/5.1/components/tooltips/#variables (this is BS v5)