Coder Wrap provides free to use snippets

*{
  box-sizing: border-box;
}

body {
  margin: 0px;
}

.gallery-wrap {
  display: flex;
  flex-direction: row;
  width: 100%;
  height: 600px;
}

.item {
  flex: 1;
  height: 100%;
  background-position: center;
  background-size: cover;
  background-repeat: none;
  transition: flex 0.8s ease;
}
.item:hover {
  flex: 7;
}