Tangentially related: what resources would y'all recommend for learning modern-ish C? I'm planning out a microcontroller project and reading through avr-libc I

Tangentially related: what resources would y'all recommend for learning modern-ish C? I'm planning out a microcontroller project and reading through avr-libc I'm realizing my C skills have completely atrophied since college a decade ago. There seems to be a lot of outdated information out there, and honestly it's tough for me to judge the quality of what I'm reading. Any advice is greatly appreciated!