body {
    padding-left: 200px;
    padding-right: 200px;
}

header {
    padding: 10px 0px 10px 0px;
}

#image-demo {
    width: 400px;
    border: solid 1px #000;
    margin: 10px;
}

main {
    display: flex;
    justify-content: space-between;
}

.box {
    width: 200px;
    height: 200px;
    display: flex;
    border: solid 1px #000;
    background-color: white;
    justify-content: center;
    align-items: center;
}