<div class="box">
  <div class="box_inside"></div>
</div>

.box {
  width: 150px;
  height: 150px;
  background-color: #e91e63;
  clip-path: polygon(20% 0, 100% 0, 100% 100%, 0 100%, 0% 20%);

  position: relative;
  border-radius:5px;
}
.box_inside{
  position: absolute;
  inset:2px;
  background: #2196f3;
  clip-path: polygon(20% 0, 100% 0, 100% 100%, 0 100%, 0% 20%);
  border-radius:5px;
}