body {
    background-color: #000;
    background-image: url("/images/wallpaper/bg.jpg");
    background-attachment: fixed;
    background-size: cover; 
    background-position: center center; }
.container {
  max-width: 800px; }
.header {
  margin-top: 25%;
  text-align: center; }
.logo {
  opacity: 0.5;
  max-width: 100%;
  height: auto;
}