.callbacks {
    position: relative;
    list-style: none;
    overflow: hidden;
    width: 100%;
    padding: 0;
    margin: 0;
}

.callbacks li {
    position: absolute;
    width: 100%;
    left: 0;
    top: 0;
}

.callbacks img {
    display: block;
    position: relative;
    z-index: 1;
    height: auto;
    width: 100%;
    border: 0;
}

.callbacks_nav {
    position: absolute;
    -webkit-tap-highlight-color: rgba(0,0,0,0);
    top: 52%;
    left: 0;
    opacity: 0.7;
    z-index: 3;
    text-indent: -9999px;
    overflow: hidden;
    text-decoration: none;
    height: 61px;
    width: 38px;
    background: transparent url("themes/themes.gif") no-repeat left top;
    margin-top: -45px;
}

.callbacks_nav.next {
    left: auto;
    background-position: right top;
    right: 0;
}
@media (min-width: 641px){
    .callbacks img {
        height: 450px;
    }
}
@media (max-width: 640px) and (min-width: 480px){
    .callbacks img {
        height: 350px;
    }
}
@media (max-width: 479px){
    .callbacks img {
        height: 250px;
    }
}