Hi, I'm Shamim Hossain
Answer some questions and I will help you to figure out the right CSS unit for your project.
Assuming you are only using these units for web development, not for print media.
fr px rem auto min-content
The fluid stuff can use fr to take up available space, or auto or min-content if you want it to match the size of the content in a given column/row.Other parts can be defined with px or rem, if you want fixed sizes.