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diff --git a/node_modules/stylus/lib/functions/contrast.js b/node_modules/stylus/lib/functions/contrast.js
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+++ b/node_modules/stylus/lib/functions/contrast.js
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+var utils = require('../utils')
+  , nodes = require('../nodes')
+  , blend = require('./blend')
+  , luminosity = require('./luminosity');
+
+/**
+ * Returns the contrast ratio object between `top` and `bottom` colors,
+ * based on http://leaverou.github.io/contrast-ratio/
+ * and https://github.com/LeaVerou/contrast-ratio/blob/gh-pages/color.js#L108
+ *
+ * Examples:
+ *
+ *     contrast(#000, #fff).ratio
+ *     => 21
+ *
+ *     contrast(#000, rgba(#FFF, 0.5))
+ *     => { "ratio": "13.15;", "error": "7.85", "min": "5.3", "max": "21" }
+ *
+ * @param {RGBA|HSLA} top
+ * @param {RGBA|HSLA} [bottom=#fff]
+ * @return {Object}
+ * @api public
+ */
+
+module.exports = function contrast(top, bottom){
+  if ('rgba' != top.nodeName && 'hsla' != top.nodeName) {
+    return new nodes.Literal('contrast(' + (top.isNull ? '' : top.toString()) + ')');
+  }
+  var result = new nodes.Object();
+  top = top.rgba;
+  bottom = bottom || new nodes.RGBA(255, 255, 255, 1);
+  utils.assertColor(bottom);
+  bottom = bottom.rgba;
+  function contrast(top, bottom) {
+    if (1 > top.a) {
+      top = blend(top, bottom);
+    }
+    var l1 = luminosity(bottom).val + 0.05
+      , l2 = luminosity(top).val + 0.05
+      , ratio = l1 / l2;
+
+    if (l2 > l1) {
+      ratio = 1 / ratio;
+    }
+    return Math.round(ratio * 10) / 10;
+  }
+
+  if (1 <= bottom.a) {
+    var resultRatio = new nodes.Unit(contrast(top, bottom));
+    result.set('ratio', resultRatio);
+    result.set('error', new nodes.Unit(0));
+    result.set('min', resultRatio);
+    result.set('max', resultRatio);
+  } else {
+    var onBlack = contrast(top, blend(bottom, new nodes.RGBA(0, 0, 0, 1)))
+      , onWhite = contrast(top, blend(bottom, new nodes.RGBA(255, 255, 255, 1)))
+      , max = Math.max(onBlack, onWhite);
+    function processChannel(topChannel, bottomChannel) {
+      return Math.min(Math.max(0, (topChannel - bottomChannel * bottom.a) / (1 - bottom.a)), 255);
+    }
+    var closest = new nodes.RGBA(
+      processChannel(top.r, bottom.r),
+      processChannel(top.g, bottom.g),
+      processChannel(top.b, bottom.b),
+      1
+    );
+    var min = contrast(top, blend(bottom, closest));
+
+    result.set('ratio', new nodes.Unit(Math.round((min + max) * 50) / 100));
+    result.set('error', new nodes.Unit(Math.round((max - min) * 50) / 100));
+    result.set('min', new nodes.Unit(min));
+    result.set('max', new nodes.Unit(max));
+  }
+  return result;
+}