diff --git a/build.py b/build.py
index 828599e..bc43eaf 100644
--- a/build.py
+++ b/build.py
@@ -14,15 +14,12 @@ TEMPLATE = """<!DOCTYPE html>
     <script defer src="https://cdn.jsdelivr.net/npm/katex@0.16.9/dist/katex.min.js"></script>
     <script defer src="https://cdn.jsdelivr.net/npm/katex@0.16.9/dist/contrib/auto-render.min.js" onload="renderMathInElement(document.body);"></script>
     <style>
-        body {
-        background-image: url('/static/images/bg-math.svg');
-        background-repeat: repeat;
-        background-size: 800px 600px;
-        background-attachment: fixed;
-        { 
+        body {{ 
             font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; max-width: 900px; margin: 0 auto; padding: 20px; line-height: 1.6; color: #333; 
-        }
-        }
+            background-image: url('/static/images/bg-math.svg');
+            background-repeat: repeat;
+            background-size: 800px 600px;
+            background-attachment: fixed; }}
         header {{ border-bottom: 2px solid #003366; padding-bottom: 10px; margin-bottom: 30px; }}
         h1 {{ color: #003366; }}
         h2 {{ color: #004080; border-bottom: 1px solid #eee; padding-bottom: 5px; margin-top: 30px; }}
