revert: 回退部分定位组件的 z-index 设置，强制重写 v-loading 的 z-index 样式

src/assets/styles/globals.scss

@@ -82,3 +82,7 @@ textarea {
     margin-left: 10px;
   }
 }
+
+.el-loading-mask {
+  z-index: 900 !important;
+}

src/layouts/components/Search/index.vue

@@ -286,7 +286,7 @@ function pageJump(url: string) {
 <style lang="scss" scoped>
 #search {
   position: fixed;
-  z-index: 4000;
+  z-index: 2000;
   top: 0;
   left: 0;
   width: 100%;

src/layouts/components/Topbar/index.vue

@@ -73,7 +73,7 @@ function pathCompile(path: string) {
 <style lang="scss" scoped>
 .topbar-container {
   position: absolute;
-  z-index: 3000;
+  z-index: 999;
   top: 0;
   display: flex;
   align-items: center;