body { background-image: url(../picture/04.jpg);
 background-attachment: fixed;
 background-position: center;
 background-size: cover;
 /*background-size: contain*/;
}
header { color: #00ffff;
 line-height: 1.2;
 font-size: 40px;
 text-align: center;
}
a { text-shadow: 1px 0px 1px #e0ffff,
 1px 0px 2px #e0ffff,
 1px 0px 6px #e0ffff;
 font-weight: bold;
 font-size: 2.5rem;
 text-align: center;
}
nav { text-align: center;
}
div { margin-top: 795px;
 text-align: center;
}