html {
    height: 100%;
}

body {
    height: 100%;
}

#container {
    display: flex;           /* establish flex container */
    flex-direction: column;  /* make main axis vertical */
    justify-content: center; /* center items vertically, in this case */
    align-items: center;     /* center items horizontally, in this case */
    height: 100%;
}

.centered {
    width: 100%;
    /* width: 300px; */
    /* margin: 5px; */
    text-align: center;     /* will center text in <p>, which is not a flex item */
}

#content-block {
    min-width: 20rem;
    width: 30%;
    text-align: center;     /* will center text in <p>, which is not a flex item */
}

#logo-image {
width: 20rem;
}