Provide an option to dismiss or close a component with `.btn-close`. Default styling is limited, but highly customizable. Modify the Sass variables to replace the default `background-image`. **Be sure to include text for screen readers**, as we've done with `aria-label`.
Disabled close buttons change their `opacity`. We've also applied `pointer-events: none` and `user-select: none` to preventing hover and active states from triggering.