I've encountered a strange bug (using Chrome for Android). When I have this CSS demo page open and scroll about halfway down, the volume of my background audio (e.g., a Twitch App stream) drops by about 50%. Closing the tab immediately restores the audio to its normal volume. I can reproduce this issue consistently. Does anyone have any idea what might be causing this behavior?

Edit: it seems it's caused by autoplay of Easing Wizard's video.