* {
    box-sizing: border-box;
}

html, body {
    font-family: arial;
    padding: 0;
    margin: 0;
    background: lightgrey;
}
.section {
    background:rgb(0,0,0);
    background:rgba(0,0,0,0.3);
    color:white;
    padding:12px;
    margin:12px;
    text-align:center;
    border-radius:12px;
}