A "Hart chart" for practicing eye scanning exercises to assist in recovery of convergence insufficiency.
Just load index.html and a letter sequence is created. Font size renders differently on mobile and screen. Use 'share' button to pass link of identical letter sequence between devices. Repeating adjacent letters shouldn't appear. No thin letters (I and J removed). Randomize a new set with 'reset' button as necessary to keep mind from getting bored of repetitious exercise over time, and share link again between devices.
Later on to do: replace with shorter seed and eliminate need for share button.
Tested primarily on Windows in Chrome, but also in Firefox, Opera, Edge, Android, and Safari.
Live version here.
