add gradient border css on hover code example

Example 1: css gradient border

box-sizing: content-box;
  border-width: 8px;
  border-style: solid;
  border-image: linear-gradient(to right bottom, #260B3C, #a053df);
  border-image-slice: 1;

Example 2: linear gradient border

div-border-and-content-background {
  border-top: double 5px transparent;
  
  /* first gradient is for card background, second for border background */
  background-image: linear-gradient(white,white), linear-gradient(to right, grey, black);
  background-clip: padding-box, border-box;
  background-origin: border-box;
  }