<ul class='circle-container'>
  <li><img src='http://lorempixel.com/100/100/city'></li>
  <li><img src='http://lorempixel.com/100/100/nature'></li>
  <li><img src='http://lorempixel.com/100/100/abstract'></li>
  <li><img src='http://lorempixel.com/100/100/cats'></li>
  <li><img src='http://lorempixel.com/100/100/food'></li>
  <li><img src='http://lorempixel.com/100/100/animals'></li>
  <li><img src='http://lorempixel.com/100/100/business'></li>
  <li><img src='http://lorempixel.com/100/100/people'></li>
</ul>

@import "compass/css3";

/// Mixin to place items on a circle
/// @author Hugo Giraudel
/// @author Ana Tudor
/// @param {Integer} $item-count - Number of items on the circle
/// @param {Length} $circle-size - Large circle size
/// @param {Length} $item-size - Single item size
@mixin on-circle($item-count, $circle-size, $item-size) {  
  position: relative;
  width:  $circle-size;
  height: $circle-size;
  border-radius: 50%;
  padding: 0; 
  list-style: none;
  
  > * {
    display: block;
    position: absolute;
    top:  50%; 
    left: 50%;
    margin: -($item-size / 2);
    width:  $item-size;
    height: $item-size;
  
    $angle: (360 / $item-count);
    $rot: 0;

    @for $i from 1 through $item-count {
      &:nth-of-type(#{$i}) {
        transform: rotate($rot * 1deg) translate($circle-size / 2) rotate($rot * -1deg);
      }

      $rot: $rot + $angle;
    }
  }
}

.circle-container {
  @include on-circle($item-count: 8, $circle-size: 20em, $item-size: 6em); 
  margin: 5em auto 0;
  border: solid 5px tomato;

  img { 
    display: block; 
    max-width: 100%; 
    border-radius: 50%;
    filter: grayscale(100%);
    border: solid 5px tomato;
    transition: .15s;
     
    &:hover {
      filter: grayscale(0);
    }
  }
}