I have used this code to force different height for intro slideshow pictures as well as the code I found on other topic that fixes some issues with mobile devices.
The site works ok on PC, but on smartphones and tablets the height stays 550 px even though the width of the pic is scaled to fit the mobile screen.
Web adress: fancy-chic.com

I used this code:

#image_intro {
  width: 920px;
  height: 550px;
  padding: 0;
  margin-top: -30px;
}
#image_intro_preview {
  margin: 0;
  padding: 0;
}

#image_intro_preview .s_button_prev_holder {
  margin-left: 35px;
}
#image_intro_preview .s_button_next_holder {
  margin-right: 35px;
}
@media only screen and (min-width: 768px) and (max-width: 991px) {
  #image_intro {
    width: 740px !important;
  }
  #image_intro_preview img {
    max-width: 740px !important;
  }
}
@media only screen and (max-width: 767px) {
  #image_intro {
    margin-top: -20px !important;
    width: 280px !important;
  }
  #image_intro_preview img {
    max-width: 280px !important;
  }
}
@media only screen and (min-width: 480px) and (max-width: 767px) {
  #image_intro {
    width: 440px !important;
  }
  #image_intro_preview img {
    max-width: 440px !important;
  }