# Browser support

> awesome-reveal uses Intersection Observer and Web Animations, both Baseline Widely available. It supports Chrome 84, Firefox 75, Safari 13.1, and has fallbacks.

awesome-reveal is built on two web APIs: Intersection Observer and Web Animations. Both are [Baseline Widely available](https://developer.mozilla.org/en-US/docs/Glossary/Baseline/Compatibility): they have worked in all the Baseline browsers for at least 2.5 years.

The packages also support older browsers: Chrome 84, Firefox 75 (79 on Android) and Safari 13.1, or later. These versions support the Web Animations API with implicit keyframes.

## Fallbacks

In browsers without a necessary API, the content still shows:

* Without `IntersectionObserver`, elements are revealed immediately.
* Without `Element.animate`, elements appear with no animation.
* When `element.animate` throws, the element appears with no animation. For example, browsers without CSS `linear()` throw on a [`spring()`](/concepts/keyframes/#springs) easing that the server created. A property value that the browser does not support does not throw: the browser ignores it.

If the browser rejects an option, such as an invalid `rootMargin`, the element shows at once. The error is reported once for each message, and it reaches `window.onerror`: it does not throw in your code.

## Implicit keyframes in Safari

The built-in keyframes end with an empty keyframe (`{}`). The browser fills it with the current style of the element. [MDN](https://developer.mozilla.org/en-US/docs/Web/API/Element/animate#browser_compatibility) marks the support of Safari for these implicit keyframes as partial. If a custom animation looks wrong in Safari, give explicit values to each keyframe.