igara/syonet_seven

.close_icon {
  position: fixed;
  top: 0;
  right: 0;
  width: 8vh;
  max-width: 80px;
  height: 8vh;
  max-height: 80px;
  padding: 0;
  text-align: center;
  vertical-align: middle;
  background: rgb(0, 0, 0);
  border: none;
  border-radius: 50%;
  outline: 0;
  cursor: pointer;
  transition: background-color 1s;
}

.close_icon:hover {
  background: rgb(255, 255, 255);
}

.close_icon.hidden {
  display: none;
}

.close_mark {
  width: 8vh;
  max-width: 80px;
  height: 10px;
  background-color: rgb(255, 255, 255);
  transform: rotate(45deg);
  transition: background-color 1s;
}

.close_mark::after {
  display: block;
  width: 100%;
  height: 100%;
  background-color: inherit;
  transform: rotate(90deg);
  content: "";
}

.close_icon:hover > .close_mark {
  background: rgb(0, 0, 0);
}