diff --git a/src/views/marketing/coupon_edit.vue b/src/views/marketing/coupon_edit.vue
index 21bc090..210056c 100644
--- a/src/views/marketing/coupon_edit.vue
+++ b/src/views/marketing/coupon_edit.vue
@@ -197,6 +197,7 @@ export default class extends Vue {
 
   private dataRange: Date[] = []
   private initContent = ''
+  private cssChanged = false
 
   get lang() {
     return AppModule.language
@@ -344,7 +345,13 @@ export default class extends Vue {
     const ctx = canvas.getContext('2d') as CanvasRenderingContext2D
     ctx.clearRect(0, 0, canvas.width, canvas.height)
     var iframedoc = iframe.contentDocument || (iframe.contentWindow?.document as Document)
-    iframedoc.body.style.margin = '0px'
+    if (!this.cssChanged) {
+      iframedoc.body.style.margin = '0px'
+      var style = iframedoc.createElement('style')
+      style.innerHTML = 'body p { margin-block-start:0;margin-block-end:0; }'
+      iframedoc.head.appendChild(style)
+      this.cssChanged = true
+    }
     html2canvas(iframedoc.body, {
       canvas,
       useCORS: true,