You don't want it too close, but it can be closer than that if you have normal eyesight. The line should be where your eyes have trouble focusing and add a small buffer. For me that's about a foot. So wherever you're comfortable looking at a smartphone (or really any object) is a good point of reference.

Otherwise this is a commonly propagated myth related to radiation from early TV sets.

https://theopticalshoppetn.com/is-sitting-too-close-to-the-t...