У вашего броузера проблема в совместимости с HTML5
Hey ninjas, in this CSS Flexbox tutorial, I'll show you how we can wrap flex items using the flex-wrap property. Flex-wrap allows us to wrap elements onto the next line when there is not enough room for them in the current row of content.
----- COURSE LINKS:
+ Source files on GitHub - https://github.com/iamshaunjp/css-flexbox-playlist
+ Brackets editor - https://brackets.io/
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