feat: add color paletee of neutral color (#5119)

src/sku/index.less

@@ -62,7 +62,7 @@
 
   &-header-item {
     margin-top: @padding-xs;
-    color: @gray-dark;
+    color: @gray-6;
     font-size: @font-size-sm;
     line-height: 16px;
   }
@@ -178,7 +178,7 @@
       }
 
       &--disabled {
-        color: @gray;
+        color: @gray-5;
         background: @active-color;
 
         .van-sku-row__item-img {
@@ -213,7 +213,7 @@
   &__stock {
     display: inline-block;
     margin-right: @padding-xs;
-    color: @gray-dark;
+    color: @gray-6;
     font-size: @font-size-sm;
 
     &-num--highlight {
@@ -334,11 +334,11 @@
       }
 
       &--warning {
-        background: linear-gradient(to right, #ffd01e, #ff8917);
+        background: @gradient-orange;
       }
 
       &--danger {
-        background: linear-gradient(to right, #ff6034, #ee0a24);
+        background: @gradient-red;
       }
     }
   }