diff --git a/404.html b/404.html
index 6418263..3c2cb40 100644
--- a/404.html
+++ b/404.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <html lang="en-US">
   <head>
     <meta charset="UTF-8" />
diff --git a/index.html b/index.html
index 808f87b..09705b9 100644
--- a/index.html
+++ b/index.html
@@ -1,9 +1,7 @@
 <!DOCTYPE html>
-<html lang="en">
+<html lang="en-US">
   <head>
     <meta charset="UTF-8" />
-    <meta http-equiv="X-UA-Compatible" content="IE=edge">
-    <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>Array in a Matrix</title>
     <link rel="stylesheet" type="text/css" href="style/main.style.css" />
   </head>
diff --git a/index/RPS/index.html b/index/RPS/index.html
index 482288f..b91e134 100644
--- a/index/RPS/index.html
+++ b/index/RPS/index.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <html lang="en-US">
   <head>
     <meta charset="UTF-8" />
diff --git a/index/projects/index.html b/index/projects/index.html
index bfc7991..e912beb 100644
--- a/index/projects/index.html
+++ b/index/projects/index.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <html lang="en-US">
   <head>
     <meta charset="UTF-8" />
diff --git a/style/index.html b/style/index.html
index 475146f..0f1522f 100644
--- a/style/index.html
+++ b/style/index.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <html lang="en-US">
   <head>
     <meta charset="UTF-8" />
