For improved cross-browser rendering, Bootstrap v{{ bootstrapVersionMinor }} uses

browsers and devices while providing slightly more opinionated resets to common

<abbr title="Hyper Text markup Language">HTML</abbr> elements.

- [Web Content Accessibility Guidelines (WCAG) 2.0](https://www.w3.org/TR/WCAG20/)

- [The A11Y Project](https://a11yproject.com/)

- [MDN accessibility documentation](https://developer.mozilla.org/en-US/docs/Web/Accessibility)

- BootstrapVue's [Theming](/docs/reference/theming) reference section

- Official Bootstrap

Various components will use variations (intensities) of these default theme colors.

You can alter the theme colors, and create additional theme colors, as needed via SASS variables and

docs for more details. All theme colors automatically become available as

[color variants](/docs/reference/color-variants) to all BootstrapVue components.

| `$enable-shadows` | Boolean | `false` | Enables predefined `box-shadow` styles on various components |

| `$enable-gradients` | Boolean | `false` | Enables predefined gradients via `background-image` styles on various components |

| `$enable-transitions` | Boolean | `true` | Enables predefined `transition`s on various components |

| `$enable-validation-icons` | Boolean | `true` | Enables `background-image` icons within textual inputs and some custom forms for validation states |

additional Bootstrap v4 variable information.

The following are convenience links to Bootstrap v4's documentation:

Bootstrap v4 also has defined typography styles and classes for various native HTML elements. You

can find out more at the following links:

Feedback will be shown if the parent `<b-form>` component does _not_ have the `novalidate` prop set

(or set to `false`) along with the `validated` prop set (and the input fails or passes native

browser validation constraints such as `required`). Refer to Bootstrap v4's

details on validation methods.

You should always provide content via the `invalid-feedback` prop (or slot) to aid users using

- `null` Displays no validation state (neither valid nor invalid)

Refer to the

for details on the new Bootstrap v4 validation states.

Additional resources:

- [MDN: Learn Form Validation - Using JavaScript API](https://developer.mozilla.org/en-US/docs/Learn/HTML/Forms/Form_validation#Validating_forms_using_JavaScript)

- [MDN: HTML5 Constraint Validation](https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/HTML5/Constraint_validation)

- [MDN: Validity State API](https://developer.mozilla.org/en-US/docs/Web/API/ValidityState)

Create equal-width columns that span multiple lines by inserting a `.w-100` where you want the

columns to break to a new line. Make the breaks responsive by mixing `.w-100` with some

There was a [Safari flexbox bug](https://github.com/philipwalton/flexbugs#flexbug-11) that prevented

this from working without an explicit `flex-basis` or `border`. There are workarounds for older