fix: 高亮显示活动

aio/content/navigation.json

@@ -26,7 +26,8 @@
     },
     {
       "url": "https://ng-china.org/",
-      "title": "**** 2018 ngChina @ 杭州！****"
+      "title": "**** 2018 ngChina @ 杭州！****",
+      "highlight": true
     }
   ],
   "TopBarNarrow": [

aio/src/app/layout/top-menu/top-menu.component.ts

@@ -3,9 +3,14 @@ import { NavigationNode } from 'app/navigation/navigation.service';
 
 @Component({
   selector: 'aio-top-menu',
+  styles: [`
+    .nav-link.highlight {
+      color: yellow;
+    }
+  `],
   template: `
     <ul role="navigation">
-      <li *ngFor="let node of nodes"><a class="nav-link" [href]="node.url" [title]="node.title">{{ node.title }}</a></li>
+      <li *ngFor="let node of nodes"><a class="nav-link" [class.highlight]="node.highlight" [href]="node.url" [title]="node.title">{{ node.title }}</a></li>
     </ul>`
 })
 export class TopMenuComponent {

aio/src/app/navigation/navigation.model.ts

@@ -8,6 +8,7 @@ export interface NavigationNode {
   tooltip?: string;
   hidden?: boolean;
   divider?: boolean;
+  highlight?: boolean;
   children?: NavigationNode[];
 }