.bigDiv {
    height: 810px;
}

.greyDiv {
    background-color: #dadada;
}

.purpleDiv {
    background-color: #800080;
}

h2,
h3,
h4,
p {
    text-align: center;
}

img {
    display: block;
    margin-left: auto;
    margin-right: auto;
    width: 97%;
}