What is this blue highlight that appears sometimes on a timeout

[jzbg]

What does this highlight mean ? Sometimes when I load a category the page will highlight a topic with a blue background... I want to know what this is used for. I want to disable this functionality.

I'm trying to catch the css class that is getting adjusted on the DOM, but its going quick and I am having trouble locating it.

UPDATE: the class appears to be called .highlight

[jzbg]

It appears that if you have long thread and you use back navigation on browser it highlights to show you the last post you clicked.