body, html {
    height: 100%;
}
body {
    color: white;
}
#background {
    width: 100%;
    height: 100%;
    position: fixed;
    left: 0px;
    top: 0px;
    z-index: -1;
}
#background img {
    width: 100%;
    height: 100%;
}
.content-area {
    padding: 10px 10px 10px 10px;
}
.dark-background-content {
    border: 1px solid white;
    border-radius: 10px;
    background-color: rgba(0,0,0,0.8);
    margin-top: 20px;
    padding: 10px 10px 10px 10px;
}
.flex-horizontal {
    display: flex;
    justify-content: center;
}
.dark-background-content.flex-horizontal > div {
    margin-left: 20px;
}

.download-button {
    background-color: darkgreen;
    padding: 10px 25px 10px 25px;
    border-radius: 5px;
    color: white;
    font-size: large;
}

.download-button:hover {
    background-color: green;
    color: white;
    text-decoration: none;
}

.align-center {
    text-align: center;
}

.remark {
    font-size: small;
}