%hidden {
  display: none !important;
  visibility: hidden;
}

%invisible {
  visibility: hidden;
}

%clearfix {
  *zoom: 1;
  &:before, &:after {
    content: " ";
    display: table;
  }
  &:after {
    clear: both;
  }
}

%visuallyhidden {
  margin: -1px;
  padding: 0;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  clip: rect(0, 0, 0, 0);
  position: absolute;
}

@mixin transition($args...) {
  -webkit-transition: $args;
  -moz-transition: $args;
  -ms-transition: $args;
  -o-transition: $args;
  transition: $args;
}

@mixin opacity($opacity) {
  opacity: $opacity;
  $opacity-ie: $opacity * 100;
  filter: alpha(opacity=$opacity-ie); //IE8
}

@mixin background-cover($img) {
  background: url($img) no-repeat center center;
  -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;
}