Animate border-top-width CSS property

To implement animation on the border-top-width property with CSS, you can try to run the following code


Live Demo

<!DOCTYPE html>
         div {
            width: 500px;
            height: 300px;
            background: yellow;
            border: 10px solid yellow;
            background-image: url('');
            animation: myanim 3s infinite;
            background-position: bottom left;
            background-size: 50px;
         @keyframes myanim {
            20% {
               background-color: maroon;
               background-size: 90px;
               border-color: red;
               border-top-width: 50px;
      <h2>Performing Animation for color of border</h2>