diff --git a/routers/web/repo/issue_content_history.go b/routers/web/repo/issue_content_history.go
index bf3571c83..a7362113e 100644
--- a/routers/web/repo/issue_content_history.go
+++ b/routers/web/repo/issue_content_history.go
@@ -156,7 +156,7 @@ func GetContentHistoryDetail(ctx *context.Context) {
 
 	// use chroma to render the diff html
 	diffHTMLBuf := bytes.Buffer{}
-	diffHTMLBuf.WriteString("<pre class='chroma' style='tab-size: 4'>")
+	diffHTMLBuf.WriteString("<pre class='chroma'>")
 	for _, it := range diff {
 		if it.Type == diffmatchpatch.DiffInsert {
 			diffHTMLBuf.WriteString("<span class='gi'>")
diff --git a/web_src/css/repo.css b/web_src/css/repo.css
index d3036744f..e44bc9811 100644
--- a/web_src/css/repo.css
+++ b/web_src/css/repo.css
@@ -2322,6 +2322,7 @@ tbody.commit-list {
   min-height: 12em;
   max-height: calc(100vh - 10.5rem);
   overflow-y: auto;
+  tab-size: 4;
 }
 
 .comment-diff-data pre {