diff --git a/src/index.html b/src/index.html
index 202f692..19155a9 100644
--- a/src/index.html
+++ b/src/index.html
@@ -1,5 +1,5 @@
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html xmlns="http://www.w3.org/1999/xhtml" xmlns="" xmlns="" xml:lang="en" lang="en">
+<!doctype html>
+<html lang="en" prefix="og: http://ogp.me/ns#">
 <head>
     <title>Samuel Philipp</title>
     <base href="/">
