News Home Page Using CSS Grid and Flex Box

As advice, I would tell you that in the body you do not add an exact width, normally it is not necessary in most cases since as default it always uses the 100vw available from the browser, and the size that you really want to be able to modify is that of your container, yes you still want to add a width to your body use the following style min-width: 100vw. To center the elements in your body with grid you only need to use two lines, display: grid; place-items: center;

For the mobile view part, you only need to add a single column template to your grid because it is the only thing you need, and accommodate the different parts of your code in the part where it would go, it is a bit more complicated to understand but not difficult, I leave you this game that explains how grid works in a didactic and interactive way: https://cssgridgarden.com/ :D