A full-screen clock turns a spare screen into a wall clock. Pick a face, press F, and the clock scales to fill the display at any size or shape. The face is vector artwork or scalable text, so it stays sharp on a 4K TV as well as on a small tablet.
To keep the screen from sleeping on a phone or tablet, leave the page open in the foreground; most browsers will keep the display on while a page is in full screen. For a lasting display you can also embed the clock on a page of your own.
More ways to tell the time
Questions
How do I make the clock full screen?
Press F, or use the Full screen button below the clock. Press Esc to exit.
Will the screen stay awake?
While the clock is full screen most devices keep the display on, but your device's own power settings have the last word.
Can I use this on a TV?
Yes — open the page in the TV's browser, or cast the browser tab to it, and press F.