@mixin vex-keyframes($name) {
    @keyframes #{$name} {
        @content;
    }

    @-webkit-keyframes #{$name} {
        @content;
    }

    @-moz-keyframes #{$name} {
        @content;
    }

    @-ms-keyframes #{$name} {
        @content;
    }

    @-o-keyframes #{$name} {
        @content;
    }
}

@mixin vex-animation($animation) {
    animation: $animation;
    -webkit-animation: $animation;
    -moz-animation: $animation;
    -ms-animation: $animation;
    -o-animation: $animation;
    -webkit-backface-visibility: hidden;
}

@mixin vex-transform($transform) {
    transform: $transform;
    -webkit-transform: $transform;
    -moz-transform: $transform;
    -ms-transform: $transform;
    -o-transform: $transform;
}

@mixin vex-preserve-3d {
    -webkit-transform-style: preserve-3d;
    -moz-transform-style: preserve-3d;
    transform-style: preserve-3d;
}

// copied from Compass (https://github.com/Compass/compass) on the 21st of January 2015:

$prefix-context: null;
$current-prefix: null;
$critical-usage-threshold: 0.01 !default;
$default-has-layout-approach: zoom !default;
$has-layout-support-threshold: $critical-usage-threshold !default;

// full mixin: https://github.com/Compass/compass/blob/stable/core/stylesheets/compass/_support.scss
@mixin box-sizing($box-model) {
    -moz-box-sizing: $box-model;
    -webkit-box-sizing: $box-model;
    box-sizing: $box-model;
}

// full mixin: https://github.com/Compass/compass/blob/stable/core/stylesheets/compass/css3/_box-shadow.scss
@mixin box-shadow($shadow...) {
    -moz-box-shadow: $shadow;
    -webkit-box-shadow: $shadow;
    box-shadow: $shadow;
}

// full mixin: https://github.com/Compass/compass/blob/stable/core/stylesheets/compass/css3/_border-radius.scss
@mixin border-radius($radius) {
    -moz-border-radius: $radius;
    -webkit-border-radius: $radius;
    border-radius: $radius;
}

// full mixin: https://github.com/Compass/compass/blob/stable/core/stylesheets/compass/css3/_transform.scss
@mixin perspective($p) {
    -moz-perspective: $p;
    -webkit-perspective: $p;
    perspective: $p;
}

// full mixin: https://github.com/Compass/compass/blob/stable/core/stylesheets/compass/css3/_transform.scss
@mixin perspective-origin($origin: 50%) {
    -moz-perspective-origin: $origin;
    -webkit-perspective-origin: $origin;
    perspective-origin: $origin;
}

// full mixin: https://github.com/Compass/compass/blob/stable/core/stylesheets/compass/_support.scss
@mixin appearance($appearance) {
    $appearance: unquote($appearance);

    -moz-appearance: $appearance;
    -webkit-appearance: $appearance;
}

@mixin has-layout($approach: $default-has-layout-approach) {
    @if support-legacy-browser("ie", "7", $threshold: $has-layout-support-threshold) {
        @if $approach == zoom {
            @include has-layout-zoom;
        }
        @else if $approach == block {
            @include has-layout-block;
        }
        @else {
            @warn "Unknown has-layout approach: #{$approach}";

            @include has-layout-zoom;
        }
    }
}

@mixin has-layout-zoom {
    @if support-legacy-browser("ie", "7", $threshold: $has-layout-support-threshold) {
        *zoom: 1;
    }
}

@mixin pie-clearfix {
    &:after {
        content: "";
        display: table;
        clear: both;
    }

    @include has-layout;
}

// full mixin: https://github.com/Compass/compass/blob/stable/core/stylesheets/compass/_support.scss
@function support-legacy-browser($browser, $min-version, $max-version: null, $threshold: $critical-usage-threshold) {
    @return true;
}