Problems centering slideshow

Question

I want to center my slideshow, only when I put the style margin: 0 auto does not centralize and this happens:

CSS code:

.slideshow {
    width:100%;
    max-width:980px;
    height:auto;
    margin:0 auto;
}

.slide {
    width:100%;
    height:auto;
    display:block;
}

.slide-1 {
    width:75%;
    height:505px;
    float:left;
}

.slide-2 {
    width:25%;
    height:250px;
    float:left;
}

.slide-3 {
    width:25%;
    height:250px;
    float:left;
}

.slide-1 img {
    width:700px;
    height:500px;
}

.slide-2 img {
    width:400px;
    height:250px;
    margin-left:-35px;
}

.slide-3 img {
    width:400px;
    height:250px;
    margin-left:-35px;
}

Answer 1

Try to put this:

.slideshow {
    position:relative;
    width:100%;
    max-width:980px;
    height:auto;
    margin:0 auto;
}