kenapa thumbnailnya sebelah kiri ada jarak padahal sebelah kanan nggak ada...

ini kenapa thumbnailnya ada jarak ya gan tapi cuma sebelah kiri ,yang kanan normal aja

kode ane:

 <?php
require_once "init.php";
require_once "view/header.php";
$super_user = $login = false;

if($_SESSION['user']){
  $login = true;
  if(cek_status($_SESSION['user']) == 1){
    $super_user = true;
  }
}

$articles = tampilkan();
if(isset($_GET['cari'])){
  $cari     = $_GET['cari'];
  $articles = hasil_cari($cari);

}
 ?>
 <script src="sweetalert/dist/sweetalert.min.js"></script>
 <link rel="stylesheet" type="text/css" href="sweetalert/dist/sweetalert.css">

 <script type="text/javascript">
   swal("Hai! Selamat datang di website JarKom!", "Disini kalian akan melihat artikel tentang seputar perkembangan teknologi informasi")
 </script>

<div class="container">
  <div class="jumbotron">
  <h1>Selamat Datang di JarKom!</h1>
  <p>Selamat Datang di situs JarKom ! Sebuah website artikel sederhana. Disini kalian bisa melihat
    artikel tentang perkembangan teknologi, Tips & trik seputar teknologi, dsb.</p>
  <a href="selengkapnya.php" class="btn btn-success btn-lg" role="button"> Lihat Selengkapnya </a>
</div>
<br>

<form action="" method="get" class="pencarian">
  <span class="glyphicon glyphicon-search" aria-hidden="true"></span>
  <input type="search" name="cari" placeholder="Cari Disini gan!...">
</form>
<br><br><br>
<div id="kontainer">
 <?php
 $blog = mysqli_query($link, "SELECT * FROM blog");
 while($row= mysqli_fetch_assoc($articles)):
   ?>
   <div class="table-row-equal">
           <div class="col-sm-6 col-md-4">
           <div class="thumbnail">

        <img class="img-responsive" src="upload/<?php echo $row['gambar']; ?>">

            <div class="caption">
           <h3><?= $row['judul']; ?></h3>

          <div id="menu_thumb">
            <p class="waktu"> <span class="glyphicon glyphicon-time" aria-hidden="true"> : </span> <?= $row['waktu']; ?> </p>
           <p class="tag"> <span class="glyphicon glyphicon-tags" aria-hidden="true"> : </span> <?= $row['tag']; ?> </p>
           <?php if($login == true): ?>
           <a href="edit.php?id=<?= $row['id']; ?>" class="btn btn-primary"> Edit </a>
           <a href="delete.php?id=<?= $row['id']; ?>" class="btn btn-danger"> Hapus </a>
         <?php endif; ?>
           <a href="single.php?id=<?= $row['id']; ?>" class="btn btn-info"> Baca artikel </a>
         </div>
       </div>
       </div>
     </div>
   </div><!--akhir thumbnail row-->
<?php endwhile; ?>
</div>
</div>

<?php
require_once "view/footer.php"
?>