getElementFromPoint优化

Co-authored-by: Copilot <copilot@github.com>

src/views/book/courseware/preview/CoursewarePreview.vue

@@ -1149,7 +1149,7 @@ export default {
       const absoluteY = courserwareRect.top + y;
       let el = document.elementFromPoint(absoluteX, absoluteY);
       // 向上查找，直到找到具有 data-id 属性和 grid 类的元素
-      while (el && !el.dataset.id && !el.classList.contains('grid')) {
+      while (el && (!el.dataset.id || !el.classList.contains('grid'))) {
         el = el.parentElement;
       }