diff --git a/convert-w2p.js b/convert-w2p.js
index 411e204..bf3261f 100644
--- a/convert-w2p.js
+++ b/convert-w2p.js
@@ -458,15 +458,25 @@ function convert(input) {
         if (hex) slideBg = { color: hex };
       }
     }
-    // fallback：从 slide name 推断背景（CSS class 设置的背景 web-to-pixso 没提取）
-    if (!slideBg) {
-      const name = sg.name.toLowerCase();
-      if (name.includes('dark')) {
-        slideBg = { color: '1A1A1A' };
-      } else if (name.includes('light')) {
-        slideBg = { color: 'FAFAFA' };
+    // fallback：从 slide 容器的文字颜色反推背景
+    if (!slideBg && slideContainer && slideContainer.styles) {
+      const textColor = slideContainer.styles.color;
+      if (textColor) {
+        const tc = rgbaToHex(textColor);
+        if (tc) {
+          const r = parseInt(tc.slice(0,2), 16);
+          const g = parseInt(tc.slice(2,4), 16);
+          const b = parseInt(tc.slice(4,6), 16);
+          const lum = (r * 299 + g * 587 + b * 114) / 1000;
+          slideBg = lum > 128 ? { color: '1A1A1A' } : { color: 'FAFAFA' };
+        }
       }
     }
+    // fallback：从 canvas 背景色兜底（最后手段）
+    if (!slideBg && canvas.backgroundColor && canvas.backgroundColor !== 'rgba(0, 0, 0, 0)') {
+      const hex = rgbaToHex(canvas.backgroundColor);
+      if (hex) slideBg = { color: hex };
+    }
     
     console.log('处理 ' + sg.name + ': ' + sg.children.length + ' 个节点');