Finding Error in My Css by NETBEANS

Question

My code is presenting the following problem in css (IMAGE ERROR MESSAGE)

error code does not interfere and I can run my site normally even with css error.

@supports ((-webkit-transform: translate3d(0, 0, 0)) or (transform: translate3d(0, 0, 0))) {
  .carousel-item {
    -webkit-transition: -webkit-transform 0.6s ease-in-out;
    transition: -webkit-transform 0.6s ease-in-out;
    -o-transition: -o-transform 0.6s ease-in-out;
    transition: transform 0.6s ease-in-out;
    transition: transform 0.6s ease-in-out, -webkit-transform 0.6s ease-in-out, -o-transform 0.6s ease-in-out;
    -webkit-backface-visibility: hidden;
            backface-visibility: hidden;
    -webkit-perspective: 1000px;
            perspective: 1000px;
  }
}