Flex has wide cross browser support. https://caniuse.com/?search=flex Please don't strip these properties from style attributes. This would include, among others, flex-grow, flex-shrink, flex-basis, flex, etc.
In a recent update Canvas was updated to allow the `flex` style property (Canvas allowlist was updated: https://tr-learncanvas.s3.amazonaws.com/docs/Canvas_HTML_Editor_Allowlist.pdf) which improves the layout options that are available, however supporting properties such as `flex-direction` or `flex-wrap` haven't been added so the layouts that are easily achieved are limited. If you want to support only the shorthand properties then supporting `flex-flow` would improve matters.
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