Oops, wait a minute. When you make the above settings, then bookmark several consecutive lines, and then move the cursor up and down from line to line, the behavior will be inconsistent (or at least I don’t understand the pattern behind it): Sometimes the text color of a particular bookmarked line will be brown, and sometimes the text color of the same bookmarked line will be black.
Here are the settings to reproduce the problem:
Current line:
Text color: custom, brown
Background color: custom, yellow
Bookmarked lines:
Text color: transparent
Background color: custom, green