With every new encounter with a word, the word will become slightly smaller, more faded, or both — just slightly more worn away.
Maybe it's a tool to explore words you're less familiar with, maybe it's a way to make reading a little more fun, or maybe it's just a silly experiment to see what books would look like if words lost their meaning the more they were used.
This tool uses things like color-mix, CSS nesting, and dialog HTML elements. If your browser is up-to-date, you will likely not face any issues aside from the ones I've inadvertently introduced.