@mixin background($alpha:0.2) {
  background-color: rgba(0, 0, 0, $alpha);
}
@mixin background-picture-fullscreen($url) {
  content:"";
  position:fixed; /* stretch a fixed position to the whole screen */
  height:100vh; /* fix for mobile browser address bar appearing disappearing */
  top:0;left:0;right:0;
  z-index:-1;
  background: url($url) center center;
  -webkit-background-size: cover; -moz-background-size: cover; -o-background-size: cover;
  background-size: cover;
}
@mixin invert($rgb:rgb(255, 255, 255), $amount:1) {
  //background-color: black;
  color: $rgb;
  mix-blend-mode: difference;
  -webkit-filter: invert($amount);
  filter: invert($amount);
}

@mixin center($pos:both ) {
  position: absolute;
  @if ($pos==both) {
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
  } @else if ($pos==top) {
    left: 50%;
    transform: translate(-50%, 0);
  } @else if ($pos==left) {
    top: 50%;
    transform: translate(0, -50%);
  } @else if ($pos==right) {
    top: 50%;
    right:0;
    transform: translate(0, -50%);
  } @else if ($pos==bottom) {
    bottom: 0;
    left:50%;
    transform: translate(-50%, 0);
  }
}

// apply the mixin to the div that surrounds your svg
// get the svg width and height from the viewbox attribute of the SVG
// see: http://mimoymima.com/sass-mixin-responsive-svgs/
@mixin responsive-svg($svgwidth, $svgheight, $containerwidth){
  width: $containerwidth; // sizes the svg
  margin: 0 auto; // centers the svg
  height: 0;
  padding-top: #{($svgheight/$svgwidth)*$containerwidth};
  position: relative;
  svg {
    position: absolute;
    top: 0;
    left: 0;
  }
}


// Flexbox Mixins
// http://philipwalton.github.io/solved-by-flexbox/
// https://github.com/philipwalton/solved-by-flexbox
//
// Copyright (c) 2013 Brian Franco
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
// This is a set of mixins for those who want to mess around with flexbox
// using the native support of current browsers. For full support table
// check: http://caniuse.com/flexbox
//
// Basically this will use:
//
// * Fallback, old syntax (IE10, mobile webkit browsers - no wrapping)
// * Final standards syntax (FF, Safari, Chrome, IE11, Opera)
//
// This was inspired by:
//
// * http://dev.opera.com/articles/view/advanced-cross-browser-flexbox/
//
// With help from:
//
// * http://w3.org/tr/css3-flexbox/
// * http://the-echoplex.net/flexyboxes/
// * http://msdn.microsoft.com/en-us/ie/hh772069(v=vs.85).aspx
// * http://css-tricks.com/using-flexbox/
// * http://dev.opera.com/articles/view/advanced-cross-browser-flexbox/
// * https://developer.mozilla.org/en-us/docs/web/guide/css/flexible_boxes

//----------------------------------------------------------------------

// Flexbox Containers
//
// The 'flex' value causes an element to generate a block-level flex
// container box.
//
// The 'inline-flex' value causes an element to generate a inline-level
// flex container box.
//
// display: flex | inline-flex
//
// http://w3.org/tr/css3-flexbox/#flex-containers
//
// (Placeholder selectors for each type, for those who rather @extend)

@mixin flexbox {
  display: -webkit-box;
  display: -webkit-flex;
  display: -moz-flex;
  display: -ms-flexbox;
  display: flex;
}

%flexbox { @include flexbox; }

//----------------------------------

@mixin inline-flex {
  display: -webkit-inline-box;
  display: -webkit-inline-flex;
  display: -moz-inline-flex;
  display: -ms-inline-flexbox;
  display: inline-flex;
}

%inline-flex { @include inline-flex; }

//----------------------------------------------------------------------

// Flexbox Direction
//
// The 'flex-direction' property specifies how flex items are placed in
// the flex container, by setting the direction of the flex container's
// main axis. This determines the direction that flex items are laid out in.
//
// Values: row | row-reverse | column | column-reverse
// Default: row
//
// http://w3.org/tr/css3-flexbox/#flex-direction-property

@mixin flex-direction($value: row) {
  @if $value == row-reverse {
    -webkit-box-direction: reverse;
    -webkit-box-orient: horizontal;
  } @else if $value == column {
    -webkit-box-direction: normal;
    -webkit-box-orient: vertical;
  } @else if $value == column-reverse {
    -webkit-box-direction: reverse;
    -webkit-box-orient: vertical;
  } @else {
    -webkit-box-direction: normal;
    -webkit-box-orient: horizontal;
  }
  -webkit-flex-direction: $value;
  -moz-flex-direction: $value;
  -ms-flex-direction: $value;
  flex-direction: $value;
}
// Shorter version:
@mixin flex-dir($args...) { @include flex-direction($args...); }

//----------------------------------------------------------------------

// Flexbox Wrap
//
// The 'flex-wrap' property controls whether the flex container is single-line
// or multi-line, and the direction of the cross-axis, which determines
// the direction new lines are stacked in.
//
// Values: nowrap | wrap | wrap-reverse
// Default: nowrap
//
// http://w3.org/tr/css3-flexbox/#flex-wrap-property

@mixin flex-wrap($value: nowrap) {
  // No Webkit Box fallback.
  -webkit-flex-wrap: $value;
  -moz-flex-wrap: $value;
  @if $value == nowrap {
    -ms-flex-wrap: none;
  } @else {
    -ms-flex-wrap: $value;
  }
  flex-wrap: $value;
}

//----------------------------------------------------------------------

// Flexbox Flow (shorthand)
//
// The 'flex-flow' property is a shorthand for setting the 'flex-direction'
// and 'flex-wrap' properties, which together define the flex container's
// main and cross axes.
//
// Values: <flex-direction> | <flex-wrap>
// Default: row nowrap
//
// http://w3.org/tr/css3-flexbox/#flex-flow-property

@mixin flex-flow($values: (row nowrap)) {
  // No Webkit Box fallback.
  -webkit-flex-flow: $values;
  -moz-flex-flow: $values;
  -ms-flex-flow: $values;
  flex-flow: $values;
}

//----------------------------------------------------------------------

// Flexbox Order
//
// The 'order' property controls the order in which flex items appear within
// their flex container, by assigning them to ordinal groups.
//
// Default: 0
//
// http://w3.org/tr/css3-flexbox/#order-property

@mixin order($int: 0) {
  -webkit-box-ordinal-group: $int + 1;
  -webkit-order: $int;
  -moz-order: $int;
  -ms-flex-order: $int;
  order: $int;
}

//----------------------------------------------------------------------

// Flexbox Grow
//
// The 'flex-grow' property sets the flex grow factor. Negative numbers
// are invalid.
//
// Default: 0
//
// http://w3.org/tr/css3-flexbox/#flex-grow-property

@mixin flex-grow($int: 0) {
  -webkit-box-flex: $int;
  -webkit-flex-grow: $int;
  -moz-flex-grow: $int;
  -ms-flex-positive: $int;
  flex-grow: $int;
}

//----------------------------------------------------------------------

// Flexbox Shrink
//
// The 'flex-shrink' property sets the flex shrink factor. Negative numbers
// are invalid.
//
// Default: 1
//
// http://w3.org/tr/css3-flexbox/#flex-shrink-property

@mixin flex-shrink($int: 1) {
  -webkit-flex-shrink: $int;
  -moz-flex-shrink: $int;
  -ms-flex-negative: $int;
  flex-shrink: $int;
}

//----------------------------------------------------------------------

// Flexbox Basis
//
// The 'flex-basis' property sets the flex basis. Negative lengths are invalid.
//
// Values: Like "width"
// Default: auto
//
// http://www.w3.org/TR/css3-flexbox/#flex-basis-property

@mixin flex-basis($value: auto) {
  -webkit-flex-basis: $value;
  -moz-flex-basis: $value;
  -ms-flex-preferred-size: $value;
  flex-basis: $value;
}

//----------------------------------------------------------------------

// Flexbox "Flex" (shorthand)
//
// The 'flex' property specifies the components of a flexible length: the
// flex grow factor and flex shrink factor, and the flex basis. When an
// element is a flex item, 'flex' is consulted instead of the main size
// property to determine the main size of the element. If an element is
// not a flex item, 'flex' has no effect.
//
// Values: none | <flex-grow> <flex-shrink> || <flex-basis>
// Default: See individual properties (1 1 0).
//
// http://w3.org/tr/css3-flexbox/#flex-property

@mixin flex($fg: 1, $fs: null, $fb: null) {

  // Set a variable to be used by box-flex properties
  $fg-boxflex: $fg;

  // Box-Flex only supports a flex-grow value so let's grab the
  // first item in the list and just return that.
  @if type-of($fg) == 'list' {
    $fg-boxflex: nth($fg, 1);
  }

  -webkit-box-flex: $fg-boxflex;
  -webkit-flex: $fg $fs $fb;
  -moz-box-flex: $fg-boxflex;
  -moz-flex: $fg $fs $fb;
  -ms-flex: $fg $fs $fb;
  flex: $fg $fs $fb;
}

//----------------------------------------------------------------------

// Flexbox Justify Content
//
// The 'justify-content' property aligns flex items along the main axis
// of the current line of the flex container. This is done after any flexible
// lengths and any auto margins have been resolved. Typically it helps distribute
// extra free space leftover when either all the flex items on a line are
// inflexible, or are flexible but have reached their maximum size. It also
// exerts some control over the alignment of items when they overflow the line.
//
// Note: 'space-*' values not supported in older syntaxes.
//
// Values: flex-start | flex-end | center | space-between | space-around
// Default: flex-start
//
// http://w3.org/tr/css3-flexbox/#justify-content-property

@mixin justify-content($value: flex-start) {
  @if $value == flex-start {
    -webkit-box-pack: start;
    -ms-flex-pack: start;
  } @else if $value == flex-end {
    -webkit-box-pack: end;
    -ms-flex-pack: end;
  } @else if $value == space-between {
    -webkit-box-pack: justify;
    -ms-flex-pack: justify;
  } @else if $value == space-around {
    -ms-flex-pack: distribute;
  } @else {
    -webkit-box-pack: $value;
    -ms-flex-pack: $value;
  }
  -webkit-justify-content: $value;
  -moz-justify-content: $value;
  justify-content: $value;
}
// Shorter version:
@mixin flex-just($args...) { @include justify-content($args...); }

//----------------------------------------------------------------------

// Flexbox Align Items
//
// Flex items can be aligned in the cross axis of the current line of the
// flex container, similar to 'justify-content' but in the perpendicular
// direction. 'align-items' sets the default alignment for all of the flex
// container's items, including anonymous flex items. 'align-self' allows
// this default alignment to be overridden for individual flex items. (For
// anonymous flex items, 'align-self' always matches the value of 'align-items'
// on their associated flex container.)
//
// Values: flex-start | flex-end | center | baseline | stretch
// Default: stretch
//
// http://w3.org/tr/css3-flexbox/#align-items-property

@mixin align-items($value: stretch) {
  @if $value == flex-start {
    -webkit-box-align: start;
    -ms-flex-align: start;
  } @else if $value == flex-end {
    -webkit-box-align: end;
    -ms-flex-align: end;
  } @else {
    -webkit-box-align: $value;
    -ms-flex-align: $value;
  }
  -webkit-align-items: $value;
  -moz-align-items: $value;
  align-items: $value;
}

//----------------------------------

// Flexbox Align Self
//
// Values: auto | flex-start | flex-end | center | baseline | stretch
// Default: auto

@mixin align-self($value: auto) {
  // No Webkit Box Fallback.
  -webkit-align-self: $value;
  -moz-align-self: $value;
  @if $value == flex-start {
    -ms-flex-item-align: start;
  } @else if $value == flex-end {
    -ms-flex-item-align: end;
  } @else {
    -ms-flex-item-align: $value;
  }
  align-self: $value;
}

//----------------------------------------------------------------------

// Flexbox Align Content
//
// The 'align-content' property aligns a flex container's lines within the
// flex container when there is extra space in the cross-axis, similar to
// how 'justify-content' aligns individual items within the main-axis. Note,
// this property has no effect when the flexbox has only a single line.
//
// Values: flex-start | flex-end | center | space-between | space-around | stretch
// Default: stretch
//
// http://w3.org/tr/css3-flexbox/#align-content-property

@mixin align-content($value: stretch) {
  // No Webkit Box Fallback.
  -webkit-align-content: $value;
  -moz-align-content: $value;
  @if $value == flex-start {
    -ms-flex-line-pack: start;
  } @else if $value == flex-end {
    -ms-flex-line-pack: end;
  } @else {
    -ms-flex-line-pack: $value;
  }
  align-content: $value;
}
