diff --git a/convert-w2p.js b/convert-w2p.js
index d724463..daa4bb8 100644
--- a/convert-w2p.js
+++ b/convert-w2p.js
@@ -634,24 +634,28 @@ async function convert(input) {
     // 额外：IMAGE 节点覆盖的 TEXT 节点也去掉（图片替代文字）
     var imageRects = sg.children.filter(c => c.type === 'IMAGE' && c.rect).map(c => ({
       x: Math.round(c.rect.x), y: Math.round(c.rect.y),
-      w: Math.round(c.rect.w), h: Math.round(c.rect.h)
+      w: Math.round(c.rect.w), h: Math.round(c.rect.h),
+      z: parseInt(c.styles?.zIndex) || 0
     }));
     var seen = {};
     var overlapRemove = new Set();
     for (var i = sg.children.length - 1; i >= 0; i--) {
       var ci = sg.children[i];
       if (!ci.rect) continue;
-      // TEXT 节点被 IMAGE 完全覆盖或包含时移除
+      // TEXT 节点被 IMAGE 覆盖时移除（IMAGE 的 z-index >= TEXT 的 z-index）
       if (ci.type === 'TEXT') {
         var cx = Math.round(ci.rect.x), cy = Math.round(ci.rect.y);
         var cw = Math.round(ci.rect.w), ch = Math.round(ci.rect.h);
+        var textZ = parseInt(ci.styles?.zIndex) || 0;
         for (var ir of imageRects) {
-          // 完全重叠
+          // 检查坐标重叠或包含
           var exactMatch = Math.abs(cx - ir.x) < 3 && Math.abs(cy - ir.y) < 3 && Math.abs(cw - ir.w) < 3 && Math.abs(ch - ir.h) < 3;
-          // TEXT 被 IMAGE 包含（IMAGE 在 TEXT 内部）
           var contained = ir.x >= cx - 5 && ir.y >= cy - 5 && ir.x + ir.w <= cx + cw + 5 && ir.y + ir.h <= cy + ch + 5;
           if (exactMatch || contained) {
-            overlapRemove.add(ci.id);
+            // IMAGE z-index >= TEXT z-index 时才移除（IMAGE 在上方）
+            if (ir.z >= textZ) {
+              overlapRemove.add(ci.id);
+            }
             break;
           }
         }
@@ -927,19 +931,22 @@ async function convert(input) {
   // ----------------------------------------------------------
   // 第三步：组装最终 Schema
   // ----------------------------------------------------------
-  // 用第一个 slide 容器的尺寸决定画布比例
+  // 画布尺寸：多 slide（PPT设计稿）用容器尺寸，单 slide（网页）用 canvas
   let layout = 'LAYOUT_16x9';
-  if (slideGroups.length > 0) {
-    const sr = slideGroups[0].slideRect;
-    if (sr && sr.w && sr.h) {
-      const sw = sr.w / 72;
-      const sh = sr.h / 72;
-      layout = 'CUSTOM';
-      return {
-        presentation: { layout: 'CUSTOM', slideWidth: sw, slideHeight: sh },
-        slides: slides
-      };
-    }
+  var sizeSource;
+  if (slideGroups.length > 1) {
+    sizeSource = slideGroups[0].slideRect;
+  } else {
+    sizeSource = { w: canvas.width || 1920, h: canvas.height || 1080 };
+  }
+  if (sizeSource.w && sizeSource.h) {
+    const sw = sizeSource.w / 72;
+    const sh = sizeSource.h / 72;
+    layout = 'CUSTOM';
+    return {
+      presentation: { layout: 'CUSTOM', slideWidth: sw, slideHeight: sh },
+      slides: slides
+    };
   }
   
   return {