[breaking change] rebuild style struct (#2021)

packages/switch/demo/index.vue

@@ -57,7 +57,7 @@ export default {
 };
 </script>
 
-<style lang="postcss">
+<style lang="less">
 .demo-switch {
   .van-switch {
     margin: 0 15px;

packages/switch/index.less

@@ -0,0 +1,45 @@
+@import '../style/var';
+
+.van-switch {
+  height: 1em;
+  width: 1.8em;
+  display: inline-block;
+  position: relative;
+  border-radius: 1em;
+  box-sizing: content-box;
+  border: 1px solid rgba(0, 0, 0, .1);
+  background-color: @white;
+  transition: background-color .3s;
+
+  &__node {
+    top: 0;
+    left: 0;
+    z-index: 1;
+    width: 1em;
+    height: 1em;
+    transition: .3s;
+    position: absolute;
+    border-radius: 100%;
+    background-color: @white;
+    box-shadow: 0 3px 1px 0 rgba(0, 0, 0, .05), 0 2px 2px 0 rgba(0, 0, 0, .1), 0 3px 3px 0 rgba(0, 0, 0, .05);
+  }
+
+  &__loading {
+    top: 25%;
+    left: 25%;
+    width: 50%;
+    height: 50%;
+  }
+
+  &--on {
+    background-color: @blue;
+
+    .van-switch__node {
+      transform: translateX(.8em);
+    }
+  }
+
+  &--disabled {
+    opacity: .4;
+  }
+}