Yes. Choose Sign in with Steam on the sign-in or sign-up page and you are in with one click.
Already have an account? Open Settings and click Link Steam account. Your Steam name and avatar show up, and you can sign in either way.
Signed up with Steam? Add your email so alerts, briefings and receipts can reach you. To also sign in with your email, set a password in Settings.
Unlinking Steam works once you can sign in another way: an email and password, or Google.
A linked Steam account also gets you a free key for the Steam data feed.
Tip: two-step verification protects Steam sign-ins too.