REPL area on PreactWWW not correctly displayed in the heading bar

[SisyphusZheng]

The REPL (interactive code environment) module on the Preact official website (https://preactjs.com/) is not rendered within the top heading bar (black navigation bar area) as expected. It appears offset or misplaced, causing layout inconsistency.

[rschristian]

Thanks.

Will be fixed in #1292 (specifically #1292 (comment)), it overflows on some specific screen sizes.