Learn how to use media queries for common device breakpoints.
Read on how to do it in this tutorial: https://www.w3schools.com/howto/howto_css_media_query_breakpoints.asp
Typical Device Breakpoints
There are tons of screens and devices with different heights and widths, so it is hard to create an exact breakpoint for each device. To keep things simple you could target five common groups:
Try it yourself here: https://www.w3schools.com/howto/tryit.asp?filename=tryhow_css_mq_breakpoints
Related Pages
CSS Tutorial: CSS Media Queries
CSS Tutorial: CSS Media Queries Examples
CSS Reference: The @media rule
RWD Tutorial: Responsive Web Design with Media Queries
JavaScript Tutorial: The window.matchMedia() method