Here is a fancy focus effect for a text field designed by Rik Schennink. When you focus on the rounded text field by clicking on it the gradient border feathers out giving it a very cool look.
If you are having trouble with the pen, try the archived copy on GitHub
Gradient Border Text Field Snippet
See the Pen Input Field Gradient Border Focus Fun by Rik Schennink (@rikschennink) on CodePen.0