#slide1 {
    background: url('images/post1.jpg') no-repeat top left;
}
#slide2 {
    background: url('images/post2.jpg') no-repeat top left;
}
#slide3 {
    background: url('images/post3.jpg') no-repeat top left;
}
#slide4 {
    background: url('images/post4.jpg') no-repeat top left;
}