How to use clip-path property for border in css

Question

I have clip-part to make "cut corner" effect.

I would like to change background to white and use green border. Problem is, when I change ba

Answer 1

add some gradient to fill the missing spaces:

.test {
  background: red;
  width: 100px;
  height: 100px;
  box-sizing:border-box;
  
  /* CORNERS */
    clip-path: polygon(10px 0%, calc(100% - 10px) 0%, 100% 10px, 100% calc(100% - 10px), calc(100% - 10px) 100%, 10px 100%, 0% calc(100% - 10px), 0% 10px);
}

.test:hover {
  --grad:transparent 49.5%,green 50%;
  background: 
    linear-gradient(to top right   ,var(--grad)) top    right,
    linear-gradient(to top left    ,var(--grad)) top    left,
    linear-gradient(to bottom right,var(--grad)) bottom right,
    linear-gradient(to bottom left ,var(--grad)) bottom left,
    white;
  background-size:13px 13px; /* 10px of the clip-path + 3px of border */
  background-repeat:no-repeat;
  background-origin:border-box;
  cursor: pointer;
  
  border: 3px solid green;
}