.chaser_ad {
    display: flex;
         /*
         justify-content: center;
         align-items: center;
          width: 100px;
          height: 100px;
          background: #fff689;
          font-size: 16px;
          font-weight: bold;
          */
    top: 0;
     /*
        transition-duration: .6s;
      */
    transition-duration: .0s;    
}

.chaser_ad.fixed {
    position: fixed;
              /*
    top: 40px;
               */
    left: auto;
    z-index: +1;
}

.chaser_ad.fixed.none {
    opacity: 0;
    z-index: -1;
}