A scss mixins file I'd like to start compiling from self-education and resources I come across while learning.

mixins.scss

/* From Sass for Web Designers by Dan Cederholm (A Book Apart No.10) */
@mixin rounded($radius){
  -webkit-border-radius: $radius;
     -moz-border-radius: $radius;
          border-radius: $radius;
}

@mixin shadow($x, $y, $blur, $color){
  -webkit-box-shadow: $x $y $blur $color;
     -moz-box-shadow: $x $y $blur $color;
          box-shadow: $x $y $blur $color;
}

@mixin shadow-inset($x, $y, $blur, $color){
  -webkit-box-shadow: inset $x $y $blur $color;
     -moz-box-shadow: inset $x $y $blur $color;
          box-shadow: inset $x $y $blur $color;
}

@mixin transition($property){
  -webkit-transition: $property .2s ease;
     -moz-transition: $property .2s ease;
       -o-transition: $property .2s ease;
          transition: $property .2s ease;
}

@mixin box-sizing{
  -webkit-box-sizing: border-box;
     -moz-box-sizing: border-box;
          box-sizing: border-box;
}

@mixin linear-gradient($from, $to){
  /*Fallback for sad browsers */
  background-color: $to;
  /* Mozilla Firefox */
  background-image:    -moz-linear-gradient($from, $to);
  /* Opera */
  background-image:      -o-linear-gradient($from, $to);
  /* Webkit (Chrome 11+) */
  background-image:        -webkit-gradient(linear, left top, left bottom, color-stop(0, $from), color-stop(1, $to));
  /* Webkit (Safari 5.1+, Chrome 10+) */
  background-image: -webkit-linear-gradient($from, $to);
  /* IE10 */
  background-image:     -ms-linear-gradient($from, $to);
  /* W3C */
  background-image:         linear-gradient($from, $to);
}

@mixin retinize($file, $type, $width, $height){
  background-image: url('../img/' + $file + '.' + $type);
  
  @media (-webkit-min-device-pixel-ratio: 1.5),
         (min--moz-device-pixel-ratio: 1.5),
         (-o-min-device-pixel-ratio: 3/2),
         (min-device-pixel-ratio: 1.5),
         (min-resolution: 1.5dppx){
    &{
      background-image: url('../img/' + $file + '-2x.' + $type);
      -webkit-background-size: $width $height;
         -moz-background-size: $width $height;
              background-size: $width $height;
    }
  }
}
/* retinize mixin refactored to allow code that can be easily maintained and reused */
$is-hidpi:" (-webkit-min-device-pixel-ratio: 1.5),
            (min--moz-device-pixel-ratio: 1.5),
            (-o-min-device-pixel-ratio: 3/2),
            (min-device-pixel-ratio: 1.5),
            (min-resolution: 1.5dppx)";

@mixin background-size($width, $height){
  -webkit-background-size: $width $height;
     -moz-background-size: $width $height;
          background-size: $width $height;
}
         
@mixin retinize($file, $type, $width, $height){
  background-image: url('../img/' + $file + '.' + $type);
  
  @media #{$is-hidpi}{
    &{
      background-image: url('../img/' + $file + '-2x.' + $type);
      @include background-size($width, $height);
      
    }
  }
}
/*From http://css-tricks.com/redesigning-with-sass/ */
@mixin vendorize($property, $value) {
	-webkit-#{$property}: $value;
	-moz-#{$property}: $value;
	-ms-#{$property}: $value;
	-o-#{$property}: $value;
	#{$property}: $value;
}