Bootstraps's less mixins for sass, way back when

_mixins.scss

// Mixins.less
// Snippets of reusable CSS to develop faster and keep code readable
// -----------------------------------------------------------------


// IE7 inline-block
// ----------------
@mixin ie7-inline-block() {
  *display: inline; /* IE7 inline-block hack */
  *zoom: 1;
}

// IE7 likes to collapse whitespace on either side of the inline-block elements.
// Ems because we're attempting to match the width of a space character. Left
// version is for form buttons, which typically come after other elements, and
// right version is for icons, which come before. Applying both is ok, but it will
// mean that space between those elements will be .6em (~2 space characters) in IE7,
// instead of the 1 space in other browsers.
@mixin ie7-restore-left-whitespace() {
  *margin-left: .3em;

  &:first-child {
    *margin-left: 0;
  }
}

@mixin ie7-restore-right-whitespace() {
  *margin-right: .3em;

  &:last-child {
    *margin-left: 0;
  }
}

// Sizing shortcuts
// -------------------------
@mixin size($width, $height) {
  width: $width;
  height: $height;
}
@mixin square($size) {
  @include size($size, $size);
}

// Placeholder text
// -------------------------
@mixin placeholder($color: $placeholderText) {
  :-moz-placeholder {
    color: $color;
  }
  ::-webkit-input-placeholder {
    color: $color;
  }
}

// Text overflow
// -------------------------
// Requires inline-block or block for proper styling
@mixin text-overflow() {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

// CSS image replacement
// -------------------------
// Source: https://github.com/h5bp/html5-boilerplate/commit/aa0396eae757
@mixin hide-text {
  font: 0/0 a;
  color: transparent;
  text-shadow: none;
  background-color: transparent;
  border: 0;
}

// FORMS
// --------------------------------------------------

// Block level inputs
@mixin input-block-level {
  display: block;
  width: 100%;
  min-height: 28px;        // Make inputs at least the height of their button counterpart
  @include box-sizing(border-box); // Makes inputs behave like true block-level elements
}


// CSS3 PROPERTIES
// --------------------------------------------------

// Border Radius
@mixin border-radius($radius) {
  -webkit-border-radius: $radius;
     -moz-border-radius: $radius;
          border-radius: $radius;
}

// Drop shadows
@mixin box-shadow($shadow) {
  -webkit-box-shadow: $shadow;
     -moz-box-shadow: $shadow;
          box-shadow: $shadow;
}

// Transitions
@mixin transition($transition) {
  -webkit-transition: $transition;
     -moz-transition: $transition;
      -ms-transition: $transition;
       -o-transition: $transition;
          transition: $transition;
}

// Transformations
@mixin rotate($degrees) {
  -webkit-transform: rotate($degrees);
     -moz-transform: rotate($degrees);
      -ms-transform: rotate($degrees);
       -o-transform: rotate($degrees);
          transform: rotate($degrees);
}
@mixin scale($ratio) {
  -webkit-transform: scale($ratio);
     -moz-transform: scale($ratio);
      -ms-transform: scale($ratio);
       -o-transform: scale($ratio);
          transform: scale($ratio);
}
@mixin translate($x, $y) {
  -webkit-transform: translate($x, $y);
     -moz-transform: translate($x, $y);
      -ms-transform: translate($x, $y);
       -o-transform: translate($x, $y);
          transform: translate($x, $y);
}
@mixin skew($x, $y) {
  -webkit-transform: skew($x, $y);
     -moz-transform: skew($x, $y);
      -ms-transform: skew($x, $y);
       -o-transform: skew($x, $y);
          transform: skew($x, $y);
}
@mixin translate3d($x, $y, $z) {
  -webkit-transform: translate($x, $y, $z);
     -moz-transform: translate($x, $y, $z);
      -ms-transform: translate($x, $y, $z);
       -o-transform: translate($x, $y, $z);
          transform: translate($x, $y, $z);
}

// Backface visibility
// Prevent browsers from flickering when using CSS 3D transforms.
// Default value is `visible`, but can be changed to `hidden
// See git pull https://github.com/dannykeane/bootstrap.git backface-visibility for examples
@mixin backface-visibility($visibility){
	-webkit-backface-visibility: $visibility;
	   -moz-backface-visibility: $visibility;
	    -ms-backface-visibility: $visibility;
	        backface-visibility: $visibility;
}

// Background clipping
// Heads up: FF 3.6 and under need "padding" instead of "padding-box"
@mixin background-clip($clip) {
  -webkit-background-clip: $clip;
     -moz-background-clip: $clip;
          background-clip: $clip;
}

// Background sizing
@mixin background-size($size){
  -webkit-background-size: $size;
     -moz-background-size: $size;
       -o-background-size: $size;
          background-size: $size;
}


// Box sizing
@mixin box-sizing($boxmodel) {
  -webkit-box-sizing: $boxmodel;
     -moz-box-sizing: $boxmodel;
      -ms-box-sizing: $boxmodel;
          box-sizing: $boxmodel;
}

// User select
// For selecting text on the page
@mixin user-select($select) {
  -webkit-user-select: $select;
     -moz-user-select: $select;
      -ms-user-select: $select;
       -o-user-select: $select;
          user-select: $select;
}

// Resize anything
@mixin resizable($direction) {
  resize: $direction; // Options: horizontal, vertical, both
  overflow: auto; // Safari fix
}

// CSS3 Content Columns
@mixin content-columns($columnCount, $columnGap: $gridGutterWidth) {
  -webkit-column-count: $columnCount;
     -moz-column-count: $columnCount;
          column-count: $columnCount;
  -webkit-column-gap: $columnGap;
     -moz-column-gap: $columnGap;
          column-gap: $columnGap;
}

// Opacity
@mixin opacity($opacity) {
  opacity: $opacity / 100;
  //filter: ~"alpha(opacity=${opacity})";
}



// BACKGROUNDS
// --------------------------------------------------

// Gradients
@mixin horizontal-three-colors($startColor: #00b3ee, $midColor: #7a43b6, $colorStop: 50%, $endColor: #c3325f) {
  background-color: mix($startColor, $endColor, 60%);
  background-image: -moz-linear-gradient(left,  $startColor 0%, $midColor $colorStop, $endColor 100%); /* FF3.6+ */
  background-image: -webkit-gradient(linear, left top, right top, color-stop(0%,$startColor), color-stop($colorStop,$midColor), color-stop(100%,$endColor)); /* Chrome,Safari4+ */
  background-image: -webkit-linear-gradient(left,  $startColor 0%,$midColor $colorStop,$endColor 100%); /* Chrome10+,Safari5.1+ */
  background-image: -o-linear-gradient(left,  $startColor 0%,$midColor $colorStop,$endColor 100%); /* Opera 11.10+ */
  background-image: -ms-linear-gradient(left,  $startColor 0%,$midColor $colorStop,$endColor 100%); /* IE10+ */
  background-image: linear-gradient(to right,  $startColor 0%,$midColor $colorStop,$endColor 100%); /* W3C */
}
@mixin horizontal($startColor: #555, $endColor: #333) {
  background-color: $endColor;
  background-image: -moz-linear-gradient(left, $startColor, $endColor); // FF 3.6+
  background-image: -ms-linear-gradient(left, $startColor, $endColor); // IE10
  background-image: -webkit-gradient(linear, 0 0, 100% 0, from($startColor), to($endColor)); // Safari 4+, Chrome 2+
  background-image: -webkit-linear-gradient(left, $startColor, $endColor); // Safari 5.1+, Chrome 10+
  background-image: -o-linear-gradient(left, $startColor, $endColor); // Opera 11.10
  background-image: linear-gradient(left, $startColor, $endColor); // Le standard
  background-repeat: repeat-x;
}
@mixin vertical($startColor: #555, $endColor: #333) {
  background-color: mix($startColor, $endColor, 60%);
  background-image: -moz-linear-gradient(top, $startColor, $endColor); // FF 3.6+
  background-image: -ms-linear-gradient(top, $startColor, $endColor); // IE10
  background-image: -webkit-gradient(linear, 0 0, 0 100%, from($startColor), to($endColor)); // Safari 4+, Chrome 2+
  background-image: -webkit-linear-gradient(top, $startColor, $endColor); // Safari 5.1+, Chrome 10+
  background-image: -o-linear-gradient(top, $startColor, $endColor); // Opera 11.10
  background-image: linear-gradient(top, $startColor, $endColor); // The standard
  background-repeat: repeat-x;
}
@mixin directional($startColor: #555, $endColor: #333, $deg: 45deg) {
  background-color: $endColor;
  background-repeat: repeat-x;
  background-image: -moz-linear-gradient($deg, $startColor, $endColor); // FF 3.6+
  background-image: -ms-linear-gradient($deg, $startColor, $endColor); // IE10
  background-image: -webkit-linear-gradient($deg, $startColor, $endColor); // Safari 5.1+, Chrome 10+
  background-image: -o-linear-gradient($deg, $startColor, $endColor); // Opera 11.10
  background-image: linear-gradient($deg, $startColor, $endColor); // The standard
}
@mixin vertical-three-colors($startColor: #00b3ee, $midColor: #7a43b6, $colorStop: 50%, $endColor: #c3325f) {
  background-color: mix($midColor, $endColor, 80%);
  background-image: -webkit-gradient(linear, 0 0, 0 100%, from($startColor), color-stop($colorStop, $midColor), to($endColor));
  background-image: -webkit-linear-gradient($startColor, $midColor $colorStop, $endColor);
  background-image: -moz-linear-gradient(top, $startColor, $midColor $colorStop, $endColor);
  background-image: -ms-linear-gradient($startColor, $midColor $colorStop, $endColor);
  background-image: -o-linear-gradient($startColor, $midColor $colorStop, $endColor);
  background-image: linear-gradient($startColor, $midColor $colorStop, $endColor);
  background-repeat: no-repeat;
}
@mixin radial($innerColor: #555, $outerColor: #333)  {
  background-color: $outerColor;
  background-image: -webkit-gradient(radial, center center, 0, center center, 460, from($innerColor), to($outerColor));
  background-image: -webkit-radial-gradient(circle, $innerColor, $outerColor);
  background-image: -moz-radial-gradient(circle, $innerColor, $outerColor);
  background-image: -ms-radial-gradient(circle, $innerColor, $outerColor);
  background-image: -o-radial-gradient(circle, $innerColor, $outerColor);
  background-repeat: no-repeat;
}
@mixin striped($color, $angle: -45deg) {
  background-color: $color;
  background-image: -webkit-gradient(linear, 0 100%, 100% 0, color-stop(.25, rgba(255,255,255,.15)), color-stop(.25, transparent), color-stop(.5, transparent), color-stop(.5, rgba(255,255,255,.15)), color-stop(.75, rgba(255,255,255,.15)), color-stop(.75, transparent), to(transparent));
  background-image: -webkit-linear-gradient($angle, rgba(255,255,255,.15) 25%, transparent 25%, transparent 50%, rgba(255,255,255,.15) 50%, rgba(255,255,255,.15) 75%, transparent 75%, transparent);
  background-image: -moz-linear-gradient($angle, rgba(255,255,255,.15) 25%, transparent 25%, transparent 50%, rgba(255,255,255,.15) 50%, rgba(255,255,255,.15) 75%, transparent 75%, transparent);
  background-image: -ms-linear-gradient($angle, rgba(255,255,255,.15) 25%, transparent 25%, transparent 50%, rgba(255,255,255,.15) 50%, rgba(255,255,255,.15) 75%, transparent 75%, transparent);
  background-image: -o-linear-gradient($angle, rgba(255,255,255,.15) 25%, transparent 25%, transparent 50%, rgba(255,255,255,.15) 50%, rgba(255,255,255,.15) 75%, transparent 75%, transparent);
  background-image: linear-gradient($angle, rgba(255,255,255,.15) 25%, transparent 25%, transparent 50%, rgba(255,255,255,.15) 50%, rgba(255,255,255,.15) 75%, transparent 75%, transparent);
}
// Reset filters for IE
@mixin pseudo {
  position:absolute;
  content:'';
  display:block;
}
@mixin font-smoothing() {
    font-smoothing:antialiased;
    -moz-font-smoothing:antialiased;
    -webkit-font-smoothing:antialiased;
}