.hex {
    display: block;
    margin: 0 auto;
    position: relative;
    width: 320px;
    height: 277.12px; /* width * 0.866 */
    background: red;
    box-sizing: border-box;
    -webkit-clip-path: polygon(0% 50%, 25% 0%, 75% 0%, 100% 50%, 75% 100%, 25% 100%);
    -moz-clip-path: polygon(0% 50%, 25% 0%, 75% 0%, 100% 50%, 75% 100%, 25% 100%);
  }
  
.hex-background {
    position: absolute;
    background-color: orange; /*color of the main-background*/
    top: 2px; /* equal to border thickness */
    left: 2px; /* equal to border thickness */
    width: 316px; /* container height - (border thickness * 2) */
    height: 273.12px; /* container height - (border thickness * 2) */
    -webkit-clip-path: polygon(0% 50%, 25% 0%, 75% 0%, 100% 50%, 75% 100%, 25% 100%);
    -moz-clip-path: polygon(0% 50%, 25% 0%, 75% 0%, 100% 50%, 75% 100%, 25% 100%);
}

.hex img {
    position: absolute;
    width: 100%; 
    height: 100%; 
    object-fit: cover;
    -webkit-clip-path: polygon(0% 50%, 25% 0%, 75% 0%, 100% 50%, 75% 100%, 25% 100%);
    -moz-clip-path: polygon(0% 50%, 25% 0%, 75% 0%, 100% 50%, 75% 100%, 25% 100%);
}