diff --git a/src/main/kotlin/html4tree/main.kt b/src/main/kotlin/html4tree/main.kt
index 2df4131..6721ea5 100644
--- a/src/main/kotlin/html4tree/main.kt
+++ b/src/main/kotlin/html4tree/main.kt
@@ -248,6 +248,11 @@ fun process_dir(curr_dir: File, excludeSet: Set<String>? = null, dirFiles: Array
                 font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
                 line-height: 1.5;
                 padding: 1rem;
+                color: #1f2328;
+              }
+              main {
+                max-width: 800px;
+                margin: 0 auto;
               }
               ul {
                 list-style-type: none;
diff --git a/src/test/kotlin/html4tree/MainTest.kt b/src/test/kotlin/html4tree/MainTest.kt
index 0a4b060..577e631 100644
--- a/src/test/kotlin/html4tree/MainTest.kt
+++ b/src/test/kotlin/html4tree/MainTest.kt
@@ -336,6 +336,8 @@ class MainTest {
         assertTrue(htmlContent.contains("padding: 1rem;"))
         assertTrue(htmlContent.contains("transition: background-color"))
         assertTrue(htmlContent.contains("prefers-reduced-motion"))
+        assertTrue(htmlContent.contains("max-width: 800px;"))
+        assertTrue(htmlContent.contains("margin: 0 auto;"))
     }
 
     @Test