[Improvement] more component use bem mixin (#932)

packages/vant-css/src/picker.css

@@ -65,17 +65,17 @@
     font-size: 17px;
     text-align: center;
 
-    li {
+    &__item {
       padding: 0 5px;
       color: $gray-darker;
-    }
 
-    li&--selected {
-      color: $black;
-    }
+      &--selected {
+        color: $black;
+      }
 
-    li&--disabled {
-      opacity: .3;
+      &--disabled {
+        opacity: .3;
+      }
     }
   }
 }

packages/vant-css/src/search.css

@@ -10,7 +10,7 @@
     padding-right: 0;
   }
 
-  &__input-wrap {
+  &__wrap {
     position: relative;
     flex: 1;
     height: 34px;
@@ -49,7 +49,7 @@
     letter-spacing: 1px;
   }
 
-  &__action-text {
+  &__cancel {
     padding: 0 10px;
     color: $green;
 

packages/vant-css/src/stepper.css

@@ -11,7 +11,8 @@
     }
   }
 
-  &__stepper {
+  &__minus,
+  &__plus {
     width: 40px;
     height: 30px;
     box-sizing: border-box;
@@ -42,10 +43,7 @@
       bottom: 0;
       background-color: #6c6c6c;
     }
-  }
 
-  &__minus,
-  &__plus {
     &:active {
       background-color: $active-color;
     }

packages/vant-css/src/swipe.css

@@ -22,23 +22,22 @@ $van-swipe-indicator: 6px;
     position: absolute;
     height: $van-swipe-indicator;
     transform: translate3d(-50%, 0, 0);
+  }
 
-    > i {
-      border-radius: 100%;
-      vertical-align: top;
-      display: inline-block;
-      background-color: $gray-dark;
-      width: $van-swipe-indicator;
-      height: $van-swipe-indicator;
-      &:not(:last-child) {
-        margin-right: $van-swipe-indicator;
-      }
+  &__indicator {
+    border-radius: 100%;
+    vertical-align: top;
+    display: inline-block;
+    background-color: $gray-dark;
+    width: $van-swipe-indicator;
+    height: $van-swipe-indicator;
+
+    &:not(:last-child) {
+      margin-right: $van-swipe-indicator;
     }
-
-    .van-swipe__indicator {
-      &--active {
-        background-color: $orange;
-      }
+  
+    &--active {
+      background-color: $orange;
     }
   }
 }