html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    padding: 0;
    font-family: sans-serif;
}

main {
    height: 100vh;
    overflow-y: scroll;
    scroll-snap-type: y mandatory;
}

main > section {
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: purple;
    scroll-snap-align: start;
    scroll-snap-stop: always;
}

main  > section:nth-child(odd) {
    background: greenyellow;
}

main > section > div {
    font-size: 80px;
    font-weight: 700;
    color: #fff;
}

/* ###################################################################################################### */
#section-4 {background: url(../image/1.jpg); background-size: cover;}
#section-5 {background: url(../image/2.jpg); background-size: cover;}
#section-6 {background: url(../image/3.jpg); background-size: cover;}

nav {position: absolute;}