Her examples look like those you can find over at gridbyexample.com. She's just showing what the differences are between Flexbox and CSS Grid, not real-world us

Her examples look like those you can find over at gridbyexample.com. She's just showing what the differences are between Flexbox and CSS Grid, not real-world usage. Responsiveness with Flexbox or CSS Grid is best achieved through media queries. You could make a really simple Flexbox or CSS Grid site with no media queries and have it be responsive, but if you want complicated layouts you'd make use of media queries. e.g. named grid-template-areas and media queries play really nice together.