Can’t figure out how to improve the compatbility with browser fallbacks. In the Basic CSS test. I tried to get a hint but there is no valid page and there is no watch a video option. Any help would be greatly appreciated.
<style>
:root {
--red-color: red;
}
.red-box {
background: var(--red-color);
height: 200px;
width:200px;
}
</style>
<div class="red-box"></div>