html, body{
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}
.blueToGreen{
    position: -webkit-sticky;
    position: sticky;
    top: 0;
    left: 0;
    width: 100px;
    height: 100px;
    background-color: blue;
    display: flex;
    justify-content: center;
    align-items: center;
}
.overflow{
    position: relative;
    background-color: #3f87a6;
    width: 200vw;
    height: 100vh;
}