Test

html{
    height:100%;
}
body  {
    background-image: url("img/bg.jpg");
    background-color: #000;
    height:100%;
}
.header{
    position: fixed; 
    width:100vw;
    left:0;
    top:0;
    padding:0px;
    background-color:#28b100;
    border-bottom: thick solid #fff;
}

.bottom{
    position:fixed;
    bottom:0;
    left:0;
}

.box{
    background: #EAFFC4;
    font-family: Arial;
    display: block; 
    width: 90%;
    color:  #000000;
    font-size: 1.25em;
    padding: 10px 20px 10px 20px;
    text-decoration: none;
    margin:0 auto;
    margin-top:10px;
    overflow: auto;
}
.btn {
    background: #28b100;
    background-image: -webkit-linear-gradient(top, #28b100, #2ba308);
    background-image: -moz-linear-gradient(top, #28b100, #2ba308);
    background-image: -ms-linear-gradient(top, #28b100, #2ba308);
    background-image: -o-linear-gradient(top, #28b100, #2ba308);
    background-image: linear-gradient(to bottom, #28b100, #2ba308);
    -webkit-border-radius: 10;
    -moz-border-radius: 10;
    border-radius: 10px;
    font-family: Arial;
    display: block; 
    width: 90%;
    color: #ffffff;
    font-size: 3em;
    padding: 10px 20px 10px 20px;
    text-decoration: none;
    text-align:center;
    margin:0 auto;
    margin-top:10px;
}

.btn:hover {
  background: #33cc33;
  text-decoration: none;
}

.skinnyimg{
    background-color:black;
    width:10em;
    height:18em;
    float:left;
    margin-right:20px;
    margin-top:10px;
}

h1{
    text-align:center;
    color:white;
    font-size: 3em;
}
img{
    width: 100%;
}