My point wasn't to replace the classic class grid, just to give basic HTML5 grid if necessary. You can always add any other CSS Framework for grid formatting. About <section> and other HTML5 tags.. you can always personalise the code to your standards.
The grid is based on this: parent element {display: flex; flex-flow: row wrap} child element {flex:1}
Replace the parent element (container) with any HTML element, replace the child element with your preferred semantic element.