The follwing 2 classes (.evenrow and .oddrow) need to be added in the style_sky_blue.css file to allow alternate colors in the address book. These classes are referenced in the openemr/interface/usergroup/addrbook_list.php file in this line of code $bgclass = (($encount & 1) ? "evenrow" : "oddrow") but not defined in the CSS file.
I gave you the syntax above. They’re definitely classes. So the first 2 are correct. Make sure you update the right css file, the one that the $css_header variable points to in the globals.php file. In my case, $css_header = “$rootdir/themes/style_sky_blue.css”, the default. So, I edited the style_sky_blue.css file. It might different on your system.