fix: Header 增加 bg 用于设置顶部 border

Bootstrap.Client/Views/Shared/Header.cshtml

@@ -1,6 +1,7 @@
 @model NavigatorBarModel
 <header class="header">
-    <div class="bg">
+    <div class="bg"></div>
+    <div class="bg-color">
         <div class="cloud">
             <div class="d-flex align-items-center bird">
                 <a id="navbar" href="#" class="sidebar-toggle-box">

Bootstrap.Client/wwwroot/css/site.css

@@ -1,9 +1,13 @@
 /*Title*/
+.bg {
+    display: none;
+}
+
 .header {
     border-bottom: 1px solid #ccc;
 }
 
-    .header .bg {
+    .header .bg-color {
         background-image: linear-gradient(to bottom, #196eac 0,#7fb4d9 100%);
     }