btn-color-modified

@@ -508,6 +508,10 @@ $yohoPage.on('touchstart', '.btn-minus', function() {
         return;
     }
 
+    if (num <= discountNum + 1) {
+        $('.btn-minus').addClass('discount-gray');
+    }
+
     if (num <= discountNum) {
         tip.show('量贩商品，' + discountNum + '件起购');
         return;
@@ -534,6 +538,10 @@ $yohoPage.on('touchstart', '.btn-minus', function() {
         return;
     }
 
+    if (num >= discountNum) {
+        $('.btn-minus').removeClass('discount-gray');
+    }
+
     if (num - 0 === leftNum || leftNum === 0) {
         return;
     }