Answers for "fade display none"

css display none transition

div {
  border: 1px solid #eee;
}
div > ul {
  visibility: hidden;
  opacity: 0;
  transition: visibility 0s, opacity 0.5s linear;
}
div:hover > ul {
  visibility: visible;
  opacity: 1;
}

fade div

Copy.box {
  -webkit-mask-image: linear-gradient(to bottom, black 0%, transparent 100%);
  mask-image: linear-gradient(to bottom, black 0%, transparent 100%);
}

css fade div

ol {
  border   : 1px #d8d8d8 dashed;
  position : relative;
}

ol:after {
  content  : "";
  position : absolute;
  z-index  : 1;
  bottom   : 0;
  left     : 0;
  pointer-events   : none;
  background-image : linear-gradient(to bottom, 
                    rgba(255,255,255, 0), 
                    rgba(255,255,255, 1) 90%);
  width    : 100%;
  height   : 4em;
}