function calc css (ok)

$offset-padding-item: 40%;

div {
      display: flex;
      justify-content: center;
      align-items: center;
      position: absolute;
      left: 50%;
      transform: translateX(-50%);
      width: calc(100% + #{$offset-padding-item} * 2);
      height: 100%;
      opacity: .5;
    }