diff --git a/src/main.rs b/src/main.rs
index 232cbc4..a492b8d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -56,7 +56,7 @@ fn print_header(header: Heading, level: usize) -> String {
     }
 
     ret.push_str(&format!(
-        "<details>\
+        "<details open='open'>\
             <summary class='sticky'><h{0}>{1}</h{0}></summary>\n\
             <div>",
         level + 2,