Here’s an emerging UI pattern: a web page loading bar. Unsatisfied with progress indicators provided by the browser, some sites are implementing their own ones to show the load status of the next page. The progress bar appears as a thin line overlaying the content, sitting right underneath the browser toolbar, growing in width across the page as the next one loads.
Here is a screenshot of the bar on Medium (the thin green line highlighted at the top):
And here is a very similar implementation on YouTube, red this time, with a subtle glow effect: