How can I allocate containers like this?

스크린샷 2021-01-07 오후 6.17.05
(Sorry for the language, just ignore the texts x)

In my css, I tried width:50%; and margin: 0px auto;into the second container as the first screenshot shows, but the result doesn’t look like the same as the second screenshot.

In this case, how can I make it correct as the second screenshot shows?