style(merch detail page): adjust header wrap top position to 0

fix the layout offset of the merchandise detail page header area

pages_promotion/merch/detail.vue

@@ -366,6 +366,10 @@ export default {
 @import './public/css/list.scss';
 </style>
 <style scoped>
+.head-wrap {
+	top: 0;
+}
+
 .merch-image-wrap {
 	width: 100rpx;
 	height: 100rpx;