As a developer, you may want to see measurements in rem while inspecting the layers in your designs for Web projects.
You can enable rem and define a root font size from the right panel of the “Spacing & Layout” page of your styleguide. When you have rem units enabled, Zeplin displays measurements and font sizes in rem while you are inspecting the layers and also in the code snippets.
You can also enable rem for measurements and font sizes separately based on your workflow. When you enable rem just for font sizes, Zeplin will display measurements in px but font sizes in rem.
Customizing the rem unit of a linked project
If your project has been linked to a styleguide, the rem settings in that styleguide will be valid for your project too. However, you can customize it just for your project from your project's styleguide. When you do this, you'll see an information note about overridden rem settings and you can revert it if you want.