Apple's iPhone X has a screen that covers the entire face of the phone, save for a "notch" to make space for a camera and other various components. The result is some awkward situations for screen design, like constraining websites to a "safe area" and having white bars on the edges. It's not much of a trick to remove it though, a
background-color on the body will do. Or, expand the website the whole area (notch be damned), you can add viewport-fit=cover to your meta viewport tag.
<meta name="viewport" content="width=device-width, initial-scale=1.0, viewport-fit=cover">
Then it's on you to account for any overlapping that normally would have been handled by the safe area. There is some new CSS that helps you accommodate for that.
... read the whole story at css-tricks.com.