逐字拆分 CSS 变量

Write a small function that walks a text node, wraps each word and each grapheme (use Intl.Segmenter) in spans, and sets style.setProperty('--i', index) on each plus '--total' on the parent. Keep an aria-label with the original string and mark spans aria-hidden. All motion then lives in CSS: transition-delay or animation-delay as calc(var(--i) * 30ms), transforms using sin()/cos() of the index for waves, and a :hover on the parent to replay. Add a line-detection pass by comparing offsetTop to expose a --line index.