       iframe.className = 'slide-frame hidden not-loaded';
            iframe.title = `PPT Slide ${index + 1}`;

            if (slidesData[index] && slidesData[index].html_content) {
                iframe.srcdoc = slidesData[index].html_content;

                iframe.onload = function() {
                    console.log(`预加载完成: 幻灯片 ${index + 1}`);
                    slideFrameCache.set(index, iframe);
                    loadingSlides.delete(index);

                    iframe.classList