Bootstrap Professional Standards & Competencies 3

Question 1

Bootstrap's color system is built on CSS custom properties prefixed with `--bs-`. What is the main professional advantage of this approach?

Accepted Answer

Colors can be overridden at runtime without recompiling Sass

Answer

CSS custom properties cascade and can be redefined in any scope at runtime, allowing theming without a Sass build step.

Question 2

Which Bootstrap breakpoint is considered 'mobile-first', meaning styles defined there apply to all larger viewports unless overridden?

Accepted Answer

xs (default, <576px)

Answer

Bootstrap's default (xs) styles apply from 0 px upward; breakpoint-suffixed classes like `col-sm-*` activate only at and above that width.

Question 3

A QA engineer notices Bootstrap tooltips are not keyboard-accessible. Which attribute must be present on the trigger element?

Accepted Answer

tabindex='0'

Answer

Non-interactive elements (like `<span>`) need `tabindex='0'` so keyboard users can focus them and trigger the tooltip.

Question 4

Which Bootstrap container class creates a full-width container that becomes fixed-width at the `lg` breakpoint?

Accepted Answer

container-lg

Answer

`container-lg` is fluid below the `lg` breakpoint and becomes max-width constrained at `lg` and above.

Question 5

When building a Bootstrap form, using `

` with `` is recommended primarily for which reason?

Accepted Answer

It groups related controls semantically for screen readers

Answer

A `

` with `` communicates the relationship between grouped controls to assistive technologies.

Bootstrap Practice Test