html {
    height: 100%;
}

body {
    min-height: 100%;

    background-image: url("riverside-church.png");
    background-size: cover;
    background-position: center top;
    display: flex;
    align-items: flex-end;
    justify-content: center;
}

.form-box
{
    padding: 2.5em;
    text-align: center;
    background-color: rgba(255,255,255,0.7);
}