.one_quarter {
      position: relative;
    }

    .image-article {
      opacity: 1;
      display: block;
      width: 100%;
      height: auto;
      transition: .5s ease;
      backface-visibility: hidden;
    }

    .one_quarter:hover .iframe-article {
      opacity: 0.3;
    }

    .one_quarter:hover .middle {
      opacity: 1;
    }

    .middle {
      transition: .5s ease;
      opacity: 0;
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      -ms-transform: translate(-50%, -50%);
      text-align: center;
    }

    .text {
      background-color: #4CAF50;
      color: white;
      font-size: 13px;
    }