This is an elegant link hover animation in CSS only designed by Bruno Almeida. When you hover over the text an underline appears to expand from left to right and when the mouse is moved away from it the underline changes colour and fades away from the left to the right. These will work well in the navigation menu.
If you are having trouble with the pen, try the archived copy on GitHub
Underline Link Hover Effect Snippet
See the Pen Nice line movement by Bruno Almeida (@brunob182) on CodePen.0