style(announcement): 调整公告表单头部样式

src/components/announcement/index.vue

@@ -292,12 +292,13 @@ export default {
   gap: 12px;
 
   .announcement-form-header {
+    padding-top: 0;
     display: flex;
     align-items: center;
     justify-content: space-between;
     padding: 12px 16px;
-    background-color: #f5f7fa;
-    border: 1px solid #e4e7ed;
+    background-color: #fff;
+    border: 0;
     border-radius: 6px;
 
     .header-left {