[bugfix] delete unnecessary style in sku (#205)

* [Document] add english document of Checkbox

* [Document] add english document of Field

* [Document] add english document of NumberKeyboard

* [bugfix] NumberKeyboard should not dispaly title when title is empty

* [Document] add english document of PasswordInput

* [Document] add english document of Radio

* [document] add english document of Switch

* [bugfix] remove redundent styles in english document

* [Document] fix details

* fix Switch test cases

* [bugfix] Swipe shouid reinitialize when item changes

* [new feature] ImagePreview reconstruct

* [new feature] add Tabbar component

* [bugfix] delete unnecessary style in sku

packages/vant-css/src/common/hairline.css

@@ -1,4 +1,4 @@
-@import "../mixins/border_retina.css";
+@import "../mixins/border-retina.css";
 
 .van-hairline {
   &,

packages/vant-css/src/sku.css

@@ -20,12 +20,7 @@
 
   &-group-container {
     margin-left: 15px;
-    position: relative;
     padding: 12px 0 2px;
-
-    &::after {
-      @mixin border-retina (bottom);
-    }
   }
 
   &-row-group {
@@ -38,13 +33,8 @@
 
   /* sku header */
   &-header {
-    position: relative;
     margin-left: 15px;
 
-    &::after {
-      @mixin border-retina (bottom);
-    }
-
     &__img-wrap {
       position: relative;
       float: left;