fix: 无 slide 容器时 fallback 到 body

测试页没有 page/slide-* 命名的容器，findSlides 返回 0。
新增 fallback：自动用 body 元素作为 slide 容器。

convert-w2p.js

@@ -421,7 +421,18 @@ async function convert(input) {
   }
 
   const canvasArea = (canvas.width || 0) * (canvas.height || 0);
-  const slideContainers = findSlides(inputRoot, canvasArea);
+  var slideContainers = findSlides(inputRoot, canvasArea);
+  // fallback：没有匹配的 slide 容器时，用 body 作为 slide
+  if (slideContainers.length === 0) {
+    function findBody(node) {
+      if (!node) return null;
+      if (node.tag === 'BODY' && node.rect) return node;
+      if (node.children) for (const c of node.children) { const r = findBody(c); if (r) return r; }
+      return null;
+    }
+    const bodyNode = findBody(inputRoot);
+    if (bodyNode) slideContainers = [bodyNode];
+  }
   console.log(`找到 ${slideContainers.length} 个 slide 容器`);
   
   const slideGroups = slideContainers.map(s => ({

web-to-ppt/convert-browser.js

@@ -140,7 +140,18 @@ async function convertToPptx(input, onProgress) {
 
   // 2. 识别 slide
   const canvasArea = (canvas.width || 0) * (canvas.height || 0);
-  const slideContainers = findSlides(inputRoot, canvasArea);
+  var slideContainers = findSlides(inputRoot, canvasArea);
+  // fallback：没有匹配的 slide 容器时，用 body 作为 slide
+  if (slideContainers.length === 0) {
+    function findBody(node) {
+      if (!node) return null;
+      if (node.tag === 'BODY' && node.rect) return node;
+      if (node.children) for (const c of node.children) { const r = findBody(c); if (r) return r; }
+      return null;
+    }
+    const bodyNode = findBody(inputRoot);
+    if (bodyNode) slideContainers = [bodyNode];
+  }
 
   // 3. 收集子节点
   const slideGroups = slideContainers.map(s => ({