Работа с изменением размера изображения

.mainblock{
    position: relative;
    width: 940px;
    z-index: 0;
    margin:82px 0 30px 230px;
}
 
.mainblock h3{
    position: absolute;
    font-family: "Arial, regular";
    font-size: 10pt;
    color: #767676;
    top: 236px;
    left: 37px;
}
 
.mainblock .mainblock_line{
    border-bottom: 1px dotted #d7d7d7;
    margin-top: -65px;
}
 
#slider2,
#slider3 {
  box-shadow: none;
  -moz-box-shadow: none;
  -webkit-box-shadow: none;
  margin: 0 auto;
  }
 
.rslides_tabs {
  font-size: 18px;
  list-style: none;
  width: 108px;
  padding: 10px 0;
  text-align: center;
  margin-left: -6px;
  margin-top: 41px;
  }
 
.rslides_tabs li {
  display: inline;
  float: none;
  margin-right: 10px;
  }
 
.rslides_tabs a {
  width: auto;
  line-height: 20px;
  padding: 9px 15px;
  height: auto;
  background: transparent;
  display: inline;
  color: #777777;
  text-decoration: none;
  background-color: #f0f0f0;
}
 
 
 
.rslides_tabs li:first-child {
  margin-left: 0;
  }
 
.rslides_tabs .rslides_here a {
  color: #000000;
  font-weight: bold;
  }
 
@media screen and (max-width: 600px) {
  h1 {
    font: 24px/50px "Helvetica Neue", Helvetica, Arial, sans-serif;
    }
  .callbacks_nav {
    top: 47%;
    }
  }
 
.rslides {
  position: relative;
  list-style: none;
  overflow: hidden;
  width: 100%;
  padding: 0;
  margin: 0;
  }
 
.rslides li {
  -webkit-backface-visibility: hidden;
  position: absolute;
  display: none;
  width: 100%;
  left: 0;
  top: 0;
  }
 
.rslides li:first-child {
  position: relative;
  display: block;
  float: left;
  }
 
.rslides img {
  display: block;
  width: 940px;
  height: 271px;
  float: left;
  height: 271px;
  border: 0;
  margin-bottom: 20px;
  }
 
 
 
.rslides .image2{
  display: block;
  width: 940px;
  height: 271px;
  float: left;
  height: 271px;
  border: 0;
  margin-bottom: 20px;
}
 
#slider2 .image1{
  position: absolute;
  display: none;
}
 
#slider2 .image2{
  position: absolute;
  display: none;
 
}
 
#slider2 .image3{
  position: absolute;
  display: none;
}
 
#slider2 .image4{
  position: absolute;
  display: none;
 
}
 
#slider2 .image5{
  position: absolute;
  display: none;
}
 
#slider2 .image6{
  position: absolute;
  display: none;
 
}
 
#slider2 li :hover .image1{
   background: url("../images/hover.png");
   display: block;
   opacity: 0.5;
 }
 
#slider2 li :hover .image2{
  background: url("../images/hover.png");
  display: block;
  opacity: 0.5;
  margin-top: 290px;
}
 
#slider2 li :hover .image3{
  background: url("../images/hover.png");
  display: block;
  opacity: 0.5;
  margin-top: 582px;
}
 
#slider2 li :hover .image4{
  background: url("../images/hover.png");
  display: block;
  opacity: 0.5;
}
 
#slider2 li :hover .image5{
  background: url("../images/hover.png");
  display: block;
  opacity: 0.5;
  margin-top: 290px;
}
 
#slider2 li :hover .image6{
  background: url("../images/hover.png");
  display: block;
  opacity: 0.5;
  margin-top: 582px;
}