css

body {
  -webkit-animation: example 20s ease 0s infinite alternate;
  animation: example 20s ease 0s infinite alternate;
  background-size: cover;
  margin: 0 auto;
}

@-webkit-keyframes example {
  0% {
    background-image: url("http://i.imgur.com/HYR1Jfl.png");
  }
  25% {
    background-image: url("http://i.imgur.com/YPPtEgB.png");
  }
  50% {
    background-image: url("http://i.imgur.com/JfhCPU7.png");
  }
  100% {
    background-image: url("http://i.imgur.com/VVj4bDc.png");
  }
}

@keyframes example {
  0% {
    background-image: url("http://i.imgur.com/HYR1Jfl.png");
  }
  25% {
    background-image: url("http://i.imgur.com/YPPtEgB.png");
  }
  50% {
    background-image: url("http://i.imgur.com/JfhCPU7.png");
  }
  100% {
    background-image: url("http://i.imgur.com/VVj4bDc.png");
  }
}

header {background: #141414; opacity: 1.0; height: 65px; width: 100%; transition: all 0.5s ease; position: fixed;}
header.sticky {height: 40px;}

#header ul {list-style-type: none;margin: 0; padding: 20px;}
#header li {display: inline;}
#header a {margin-left: 20px;color: white;text-decoration: none;font-size: 20px;float: left;}
#header a:hover {color: #FF6666;}
#header.sticky a {font-size: 16px;margin-top:-10px;}

#staff div {display: inline-block;}

#login {width: 250px;background: white;float: left;margin-top: 75px; position: fixed; transition: all 0.5s ease;}
#login p {padding: 5px 10px;}
#login.sticky {margin-top: 50px;}
#login img {text-align: center;}

button.login {border: 1px solid #662929; background-color: #ff6666; width: 200px; padding: 8px 10px;}
button.login:hover {border: 1px solid #662929; background-color: #993D3D; width: 200px; padding: 8px 10px;}

button.tr {border: 1px solid #662929; background-color: #ff6666; width: 100%; padding: 8px 10px; color: white; font-weight: bold;}
button.tr:hover {border: 1px solid #662929; background-color: #993D3D; width: 100%; padding: 8px 10px;}

button.tr-b1 {border: 1px solid #662929; background-color: #ff6666; width: 100%; padding: 8px 10px; color: white; font-weight: bold;}
button.tr-b1:hover {border: 1px solid #662929; background-color: #993D3D; width: 100%; padding: 8px 10px;}