代码优化，结构调整，进度50%

src/layout/components/AppMain.vue

@@ -0,0 +1,49 @@
+<template>
+  <section class="app-main">
+    <transition name="fade-transform" mode="out-in">
+      <keep-alive :include="cachedViews">
+        <router-view :key="key"/>
+      </keep-alive>
+    </transition>
+  </section>
+</template>
+
+<script>
+export default {
+  name: 'AppMain',
+  computed: {
+    cachedViews() {
+      return this.$store.state.tagsView.cachedViews
+    },
+    key() {
+      return this.$route.fullPath
+    }
+  }
+}
+</script>
+
+<style lang="scss" scoped>
+  .app-main {
+    z-index: 88;
+    /*84 = navbar + tags-view = 50 +34 */
+    min-height: calc(100vh - 84px);
+    width: 100%;
+    position: relative;
+    overflow: hidden;
+  }
+
+  .fixed-header+.app-main {
+    padding-top: 50px;
+  }
+
+  .hasTagsView {
+  .app-main {
+    min-height: calc(100vh - 84px);
+  }
+
+  .fixed-header+.app-main {
+    padding-top: 85px;
+  }
+  }
+</style>
+