Placeholder Text in PDF Form

I'm looking to create a PDF form where there is grayed placeholder text (i.e. "Name") that disappears when the user inserts their cursor, and then when they type, black text appears and remains.

I've seen an explanation of how I can using coding in the Properties Menu/Format/Custom, but I can't seem to make it do the gray to black thing.

Any help or link to information would be greatly appreciated.