Carousel - Relative Slide Width
Dottoro Slider allows you to specify percentage width for the slides. You can do it from CSS or in the wizard. In the next example, always three slides are visible regardless of the width of the website. Resize the window to see the magic.
Dimension > Context Dependent Slide Width: Enabled
Slide Settings > Item Width: 33.33%
Slide Settings > Media Width: 314 - performance optimization (the maximum width of the slides is 314 pixels on this page, no need larger images to download)