the time of the fading is so short, and if a topic is out of filed of view in the topic list (for example it’s the 30’th topic in the list), the blue fades to white before you reach the topic.
p.s.: the gray color of the clicked topic is also useful here in this case, and it makes me think the line is not that much needed in the case i asked for.
meanwhile I read meta.discourse every while i find some time, and a hard time is those times that i lost my previous reading position, and I need to scroll to find it again. and I think this can happen in high-dynamics forum as well.