How to adjust box size on different computer screens

[jqfdesigns]

I have a website and im trying to figure out how can i adjust the size of the box to adjust with the width of any computer seen on.

[jqfdesigns]

[stetim94]

we have @media, which we can use:

@media

this docs show one example of using max-width, you can also use min-width, this allows different css rules for different screen sizes