html, body {
    height: 100%;
}

body { 
    background: url("160436.png"); 
    font-family: Helvetica , "游ゴシック" , "Yu Gothic" , sans-serif;
}

h1 {
    font-size: 400%;
    text-shadow: 0 0 8px rgba(0,0,0,0.8), 0 0 1em rgba(0,0,0,0.9);
}

div.opacity-container {
    height: 100%;
    width: 100%;
    padding: 30px;
    background-color: rgba(255,255,255,0.5);
}