When highlight current line is true in gtk.sourceview (version 4), highlight color makes text unreadable in dark mode

### What Happened?

When a Gtk.SourceView (version 4 or later) widget is instantiated and sets the "highlight_current_line" property to a value of true, using a dark mode system setting does not seem to change the color of the highlighted line, making the text color nearly impossible to read.

### Steps to Reproduce

See "What Happened" description.

### Expected Behavior

When in dark mode, the highlight line color should be adjusted to a darker (but not as dark color as the text background) to help make both the text readable and the highlight line indicator visible.

### OS Version

6.x (Odin)

### Software Version

Latest release (I have run all updates)

### Log Output

_No response_

### Hardware Info

_No response_