The footer CSS has position: absolute and had a variable height. Since the footer can contain error messages from plugins, the height would grow to cover up actual content (console logs, etc.).

For example, the scm-sync-configuration plugin has the option to put scm failures in the footer. It adds as many newlines are there are failing commits, which can be many lines until someone fixes the problem or clears the log. The footer expands upwards and occludes the console log, which makes diagnosing failed builds problematic.

Display SCM Sync Status
Displays a SCM Sync Configuration status health on the bottom of your Jenkins pages.
It is generally useful to activate this in order to be aware of a synchronization problem (due, for instance, to repository credentials change)

See the attached screenshot. When