body {
    background-image: url(collagebase.gif);
    background-size: cover;
    overflow: hidden;
}
html:before {
content: " ";
display: block; position: fixed;
top: 0; left: 0; bottom: 0; right: 0;
background: linear-gradient(rgba(0,0,0,0) 50%, rgba(0,0,0,0.14) 50%);
z-index: 2;
background-size: 100% 2px, 3px 100%;
pointer-events: none; 
}
#pic1 {
    position: absolute;
    height: 50%;
    margin-top: 25%;
    margin-left: -5%;
    z-index: 5;
}
#pic2 {
    position: absolute;
    height: 40%;
    margin-left: 55%;
    margin-top: 5%;
}
#pic3 {
    position: absolute;
    height: 70%;
    margin-left: 50%;
        margin-top: 28%;
        z-index: 0;
}
#pic4 {
    position: absolute;
    height: 10%;
    margin-left: 10%;
}
#pic5 {
    position: absolute;
    height: 30%;
    margin-left: 38%;
    margin-top: 30%;
    z-index: 5;
}
#pic6 {
    position: absolute;
    height: 30%;
    margin-left: 50%;
    margin-top: 22%;
}
#pic7 {
    position: absolute;
    height: 10%;
    margin-left: 70%;
}
#pic8 {
    position: absolute;
    height: 30%;
    margin-left: 60%;
}
#pic9 {
    position: absolute;
    height: 30%;
    margin-left: 50%;
    margin-left: 10%;
}
#pic10 {
    position: absolute;
    height: 60%;
    margin-left: 20%;
    margin-top: 10%;


}
#pic11 {
    position: absolute;
    height: 60%;
    margin-left: 40%;
    margin-top: 10%;
}
#pic12 {
    position: absolute;
    height: 30%;
    margin-left: -2%;
    z-index: -1;
    margin-top: 3%;
}
#pic13 {
    position: absolute;
    height: 30%;
    margin-left: 50%;
}
#pic14 {
    position: absolute;
    height: 45%;
    margin-top: 2%;
}
#pic15 {
    position: absolute;
    z-index: -2;
    height: 20%;
    margin-left: 26%;
    margin-top: -2%;
}
#pic16 {
    position: absolute;
    height: 30%;
    margin-left: 40%;
    margin-top: 40%;

}
#pic17 {
    position: absolute;
    height: 20%;
    margin-left: 52%;
    margin-top: 33%;

}
#pic18 {
    position: absolute;
    height: 20%;
    margin-left: 75%;
    margin-top: 25%;

}
#pic19 {
    position: absolute;
    height: 20%;
    margin-left: 80%;
    margin-top: 36%;

}

#pic20 {
    position: absolute;
    height: 20%;
    margin-left: 80%;
    margin-top: 32%;
    z-index: -1;

}
#pic21 {
    position: absolute;
    height: 20%;
    margin-left: 85%;
    margin-top: 3%;

}