.cut-image {
  width: 300px;        /* set desired size */
  max-width: 80%;     /* responsive */
}

.cut-image img {
  width: 100%;
  height: auto;
  display: block;

  clip-path: polygon(
    40px 0,        /* top-left cut */
    100% 0,
    100% calc(100% - 40px), /* bottom-right cut */
    calc(100% - 40px) 100%,
    0 100%,
    0 40px
  );
}