Restoring vertical column separators in SS4.3 gridfield

Silverstripe Version:
How can I restore the vertical column separators that showed in SS 3.6 in SS4.3?

I am using a ModelAdmin in SS 4.3 and want to have the vertical column separators show up as they do in SS 3.6. Also the old background alterating for odd and even columns was useful to editing and I would like to restore that. I assume I need to include some custom css somehow?

You can add custom CSS to the admin system fairly easily: