fix html validator errors/warnings

pages/search/enhanced-results.html

@@ -889,7 +889,7 @@
                         <div class="list-group-item">
                             <div class="row">
                                 <div class="col-auto">
-                                    <iframe width="240" height="160" src="https://www.youtube.com/embed/WEkSYw3o5is?controls=0" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
+                                    <iframe width="240" height="160" src="https://www.youtube.com/embed/WEkSYw3o5is?controls=0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" class="border-0" allowfullscreen></iframe>
                                 </div>
                                 <div class="col px-4">
                                     <div>

pages/search/enhanced.html

@@ -801,17 +801,10 @@
 
   <!-- Content Wrapper. Contains page content -->
   <div class="content-wrapper">
-    <!-- Content Header (Page header) -->
-    <section class="content-header">
-      <div class="container-fluid">
-        <h2 class="text-center display-4">Enhanced Search</h2>
-      </div>
-      <!-- /.container-fluid -->
-    </section>
-
     <!-- Main content -->
     <section class="content">
         <div class="container-fluid">
+            <h2 class="text-center display-4">Enhanced Search</h2>
             <form action="enhanced-results.html">
                 <div class="row">
                     <div class="col-md-10 offset-md-1">

pages/search/simple-results.html

@@ -854,7 +854,7 @@
                         <div class="list-group-item">
                             <div class="row">
                                 <div class="col-auto">
-                                    <iframe width="240" height="160" src="https://www.youtube.com/embed/WEkSYw3o5is?controls=0" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
+                                    <iframe width="240" height="160" src="https://www.youtube.com/embed/WEkSYw3o5is?controls=0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" class="border-0" allowfullscreen></iframe>
                                 </div>
                                 <div class="col px-4">
                                     <div>

pages/search/simple.html

@@ -799,16 +799,11 @@
 
   <!-- Content Wrapper. Contains page content -->
   <div class="content-wrapper">
-    <!-- Content Header (Page header) -->
-    <section class="content-header">
-      <div class="container-fluid">
-        <h2 class="text-center display-4">Search</h2>
-      </div>
-    </section>
 
     <!-- Main content -->
     <section class="content">
         <div class="container-fluid">
+            <h2 class="text-center display-4">Search</h2>
             <div class="row">
                 <div class="col-md-8 offset-md-2">
                     <form action="simple-results.html">