无法在php中使用css样式表

I am unable to style the table in css even though i have insert style for the tables.

<style>
table, th, td 
{
border: 1px solid black;
}
</style>

The above is a simple style for the codes

<div class="container">
    <table class="u-full-width">
    <?php


      $result=mysqli_query($connection,"SELECT * FROM register");

  }
  else
  {
      $result=mysqli_query($connection,"SELECT * FROM Persons WHERE username LIKE '".$Search."%'");
  }
  echo "<table border='1'>
  <tr>
  <th>username</th>
  <th>password</th>
  <th>Name</th>
  <th>gender</th>
  <th>age</th>
  <th>Contact</th>
  <th>address</th>
  <th>email</th>
  <th>occupation</th>     
  </tr>";

    while($row=mysqli_fetch_array($result))
  {
      echo "<tr>";
      echo "<td>" . $row['Username'] . "</td>"; 
      echo "<td>" . $row['password'] . "</td>";
      echo "<td>" . $row['Name'] . "</td> ";
      echo "<td>" . $row['gender'] . "</td>";
      echo "<td>" . $row['age'] . "</td> ";
      echo "<td>" . $row['contact'] . "</td>";
      echo "<td>" . $row['address'] . "</td>";
      echo "<td>" . $row['email'] . "</td>";
      echo "<td>" . $row['occupation'] . "</td>";
      echo "</tr>";
  }
  echo"</table>";
  mysqli_close($connection);
  ?>
     </div>
     </table>

The above is for displaying the tables. May i know what i can do so that it displays the table with the css. Thanks.

Its because your inserting the table dynamically with php.

try this

<div class="container">
<table class="u-full-width" border='1'>
<?php

if () {//note code is incomplete, might be copy pasting issue
  $result=mysqli_query($connection,"SELECT * FROM register");

}
else
{
  $result=mysqli_query($connection,"SELECT * FROM Persons WHERE username LIKE '".$Search."%'");
}
?>

<tr>
<th>username</th>
<th>password</th>
<th>Name</th>
<th>gender</th>
<th>age</th>
<th>Contact</th>
<th>address</th>
<th>email</th>
<th>occupation</th>     
</tr>

<?php
while($row=mysqli_fetch_array($result))
{
  echo "<tr>";
  echo "<td>" . $row['Username'] . "</td>"; 
  echo "<td>" . $row['password'] . "</td>";
  echo "<td>" . $row['Name'] . "</td> ";
  echo "<td>" . $row['gender'] . "</td>";
  echo "<td>" . $row['age'] . "</td> ";
  echo "<td>" . $row['contact'] . "</td>";
  echo "<td>" . $row['address'] . "</td>";
  echo "<td>" . $row['email'] . "</td>";
  echo "<td>" . $row['occupation'] . "</td>";
  echo "</tr>";
}
mysqli_close($connection);
?>

</table>
 </div>
 </table>

This way your table code is loaded with the page, and any information from the database is dynamically loaded

You can style easily. echo of html is bad practice. so kidly check the below way.

<table border='1'>
<tr>
<th>username</th>
<th>password</th>
<th>Name</th>
<th>gender</th>
<th>age</th>
<th>Contact</th>
<th>address</th>
<th>email</th>
<th>occupation</th>     
</tr>


while($row=mysqli_fetch_array($result)){ ?>
 <tr>
   <td><?php echo $row['Username']; ?></td>
   <td><?php echo $row['password']; ?></td>
   <td><?php echo $row['Name']; ?></td>
   <td><?php echo $row['gender']; ?></td>
   <td><?php echo $row['age']; ?></td>
   <td><?php echo $row['contact']; ?></td>
   <td><?php echo $row['address']; ?></td>
   <td><?php echo $row['email']; ?></td>
   <td><?php echo $row['occupation']; ?></td>
 </tr>
<?php } ?>
</table>
<?php mysqli_close($connection); ?>
?>

and in CSS you can use as before.

table, th, td { border: 1px solid black; }

Hope this will help you!!!