A bunch of pure CSS underline effects that can be used for links on your webpages, these were designed by Jordan Marshall. The effects include: a rainbow, slanted rainbow, shrinking underline, growing underline, double underline, triple underline, dotted underline, weave underline, various shades, etc
If you are having trouble with the pen, try the archived copy on GitHub
Colorful Link Snippet
See the Pen Cool CSS Underline Effects by Jordan Marshall (@TheCSSKing) on CodePen.default