body {
    background-image: url(images/seila-bg.jpg);
    background-color: #0f0f0f;
    background-position: center top;
    background-repeat: no-repeat;
    background-attachment: fixed;
    background-size: cover;
}

div.logo {
    width: 100%;
    text-align: center;
    margin-top: 10%;
    padding: 10px;
    box-sizing: border-box;
}

img {
    width: auto;
    max-width: 100%;
}