.slide-section {        
    position:relative;
    z-index:1;
    height:800px;
    width:100%;
    background-attachment:fixed;    /* this keeps the background in place */
    background-size:100%;
    background-repeat:no-repeat;
}
.slide-content {
    display:block;
    width:100%;
    position:relative;
    z-index:2;
    background-color:#fff;
    border:none;    
    padding:3%;
    font-size:1.4em;
    height:100px;    /* this height difference allows the bg to show through */    
    background-color: #fff;
    text-align: center;
}
.slide-section#s1 {
    background-image: url("../images/kostka-gladka.jpg");
}
.slide-section#s2 {
    background-image: url("../images/kostka-plukana.jpg");
}
.slide-section#s3 {    
    background-image: url("../images/kostka-postarzana.jpg");
}



@media (max-width: 1439px) {
  .slide-section {background-size:150%; }
  html, body {max-width: 100%;overflow-x: hidden;  }
}

@media (max-width: 1024px) {
  .slide-section {background-size:180%; }

}

@media (max-width: 768px) {
  .slide-section {background-size:350%; }

}