Generated by SassMeister.com.

SassMeister-input-HTML.html

<div class="color">
  <span class="old">Old Color:</span>
  </br>
  <span class="new">New Color:</span>
</div>

<div class="small">
  <a href="#" class="old">Original Color</a>
  <a href="#" class="new">Constrasted Color</a>
</div>

<div class="medium">
  <a href="#" class="old">Original Color</a>
  <a href="#" class="new">Constrasted Color</a>
</div>

<div class="large">
  <a href="#" class="old">Original Color</a>
  <a href="#" class="new">Constrasted Color</a>
</div>

<div class="links">
  <a href="http://juicystudio.com/services/luminositycontrastratio.php#specify">Luminosity Contrast Ration</a>
  </br>
  <a href="http://webaim.org/resources/contrastchecker/">Contrast Checker</a>
</div>

SassMeister-input.scss

// ----
// Sass (v3.3.0.rc.2)
// Compass (v1.0.0.alpha.17)
// ----

$fg-color: white;
$bg-color: #26a7df;

// ----
// Sass (v3.3.0.rc.2)
// Compass (v1.0.0.alpha.17)
// ----

// == SCSS Color Methods for Accessibility ================================
 
// Adjust given colors to ensure that those color combination provide
// sufficient contrast
 
// Methods using calculations from:
// * "Techniques For Accessibility Evaluation And Repair Tools (AERT)"
//   working draft @see http://www.w3.org/TR/AERT#color-contrast
 
// TODO: add methods with WCAG2 formulas
 
// @version 0.1
// @link http://eye48.com/go/scsscontrast
 
// @license http://www.gnu.org/licenses/lgpl.html GNU Lesser General Public License (LGPL)
// @author Michael Haschke, http://michael.haschke.biz/
 
// -- AERT ----------------------------------------------------------------
 
@function color_adjust_contrast_AERT(
                            $color_adjust,
                            $color_keep,
                            $lightness_change_value:1,
                            $saturation_change_value:1,
                            $brightness_min: 75,
                            $difference_min: 500)
{
 
    @if (color_test_contrast_AERT($color_adjust, $color_keep, $brightness_min, $difference_min) == true)
    {
        @return $color_adjust;
    }
 
    $color_save: $color_adjust;
    $S: saturation($color_adjust);
    $L: lightness($color_adjust);
    
    $foundresult: false;
    @while(($foundresult == false) and ($S > 0 or ($L > 0 and $L < 100)))
    {
        $color_adjust: desaturate($color_adjust, $saturation_change_value);
        
        $S: $S - $saturation_change_value;
        @if (lightness($color_keep) > lightness($color_adjust))
        {
             $color_adjust: darken($color_adjust, $lightness_change_value);
             $L: $L - $lightness_change_value;
        }
        @else
        {
             $color_adjust: lighten($color_adjust, $lightness_change_value);
             $L: $L + $lightness_change_value;
        }
        $foundresult: color_test_contrast_AERT($color_adjust, $color_keep, $brightness_min, $difference_min);
    }
    
    @if ($foundresult == false)
    {
        @debug $color_save + " was adjusted to " + $color_adjust + " but this is not enough contrast to " + $color_keep + " (AERT).";
    }
    
    @return $color_adjust;
}
 
@function color_test_contrast_AERT($color_1, $color_2, $brightness_min: 75, $difference_min: 500)
{
    $difference_brightness: math_absolute(color_brightness_AERT($color_1) - color_brightness_AERT($color_2));
    $difference_color: color_difference_AERT($color_1, $color_2);
    
    @if (($difference_brightness < $brightness_min) or ($difference_color < $difference_min))
    {
        @return false;
    }
    @else
    {
        @return true;
    }
}
 
@function color_brightness_AERT($color)
{
    $r: red($color);
    $g: green($color);
    $b: blue($color);
    
    @return (($r * 299) + ($g * 587) + ($b * 114)) / 1000;
}
 
@function color_difference_AERT($color1, $color2)
{
    $r1: red($color1);
    $g1: green($color1);
    $b1: blue($color1);
    
    $r2: red($color2);
    $g2: green($color2);
    $b2: blue($color2);
    
    @return (math_max($r1, $r2) - math_min($r1, $r2)) + (math_max($g1, $g2) - math_min($g1, $g2)) + (math_max($b1, $b2) - math_min($b1, $b2));
}
 
// -- math stuff ----------------------------------------------------------
 
@function math_max($value1, $value2)
{
    @if ($value1 > $value2) { @return $value1; }
    @return $value2;
}
 
@function math_min($value1, $value2)
{
    @if ($value1 < $value2) { @return $value1; }
    @return $value2;
}
 
@function math_absolute($value)
{
    @if ($value > 0) { @return $value; }
    @return $value * -1;
}

@mixin set_font_size($size) 
{
  font-size: $size + px;
  &:after {
    content: " " + $size + "px";
  }
}

@function get_new_color($fg-color, $bg-color)
{
  $color: color_adjust_contrast_AERT($bg-color, color_adjust_contrast_AERT($fg-color, $bg-color));
  @return $color;
}

.color,
.small,
.medium,
.large {
  font-family: Helvetica, arial, sans-serif;
  margin-bottom: 20px;
  
  a {
    padding: 8px 15px;
  }
  
  &:after,
  &:before {
    content: "";
    display: table;
  }
  
  &:after {
    clear:both;
  }
}

.small {
  a {
    @include set_font_size(12);  
  }
}

.medium {
  a {
    @include set_font_size(16); 
  }
}

.large {
  a {
    @include set_font_size(30); 
  }
}

$new_color: get_new_color($fg-color, $bg-color);

span {
  &.old {
    color: $bg-color;
    &:after {
      content: " " + $bg-color;
    }
  }
  &.new {
    color: $new_color;
    &:after {
      content: " " + $new_color;
    }
  }
}

a {
  display: inline-block;
  text-decoration: none;
  
  &.old {
    color: $fg-color;
    background: $bg-color;
  }
  
  &.new {
    color: $fg-color;
    background: $new_color;
  }
}

SassMeister-output.css

.color,
.small,
.medium,
.large {
  font-family: Helvetica, arial, sans-serif;
  margin-bottom: 20px;
}
.color a,
.small a,
.medium a,
.large a {
  padding: 8px 15px;
}
.color:after, .color:before,
.small:after,
.small:before,
.medium:after,
.medium:before,
.large:after,
.large:before {
  content: "";
  display: table;
}
.color:after,
.small:after,
.medium:after,
.large:after {
  clear: both;
}

.small a {
  font-size: 12px;
}
.small a:after {
  content: " 12px";
}

.medium a {
  font-size: 16px;
}
.medium a:after {
  content: " 16px";
}

.large a {
  font-size: 30px;
}
.large a:after {
  content: " 30px";
}

span.old {
  color: #26a7df;
}
span.old:after {
  content: " #26a7df";
}
span.new {
  color: #25647f;
}
span.new:after {
  content: " #25647f";
}

a {
  display: inline-block;
  text-decoration: none;
}
a.old {
  color: white;
  background: #26a7df;
}
a.new {
  color: white;
  background: #25647f;
}

SassMeister-rendered.html

<div class="color">
  <span class="old">Old Color:</span>
  </br>
  <span class="new">New Color:</span>
</div>

<div class="small">
  <a href="#" class="old">Original Color</a>
  <a href="#" class="new">Constrasted Color</a>
</div>

<div class="medium">
  <a href="#" class="old">Original Color</a>
  <a href="#" class="new">Constrasted Color</a>
</div>

<div class="large">
  <a href="#" class="old">Original Color</a>
  <a href="#" class="new">Constrasted Color</a>
</div>

<div class="links">
  <a href="http://juicystudio.com/services/luminositycontrastratio.php#specify">Luminosity Contrast Ration</a>
  </br>
  <a href="http://webaim.org/resources/contrastchecker/">Contrast Checker</a>
</div>