use Mojolicious::Lite;
  # /with_layout
  get '/a' => sub {  my $self = shift;} ;
  get '/b' => sub { my $self = shift;} ; 
  get '/c' => sub { my $self = shift;};
app->start;
__DATA__
@@ a.html.ep
  <!DOCTYPE html>
  <html>
    <head><title><%= title %></title></head>
    <body><%= content %></body>
 <table border="1">
<tr>
<td>row 1, cell 1</td>
<td>row 1, cell 2</td>
</tr>
<tr>
<td>row 2, cell 1</td>
<td>row 2, cell 2</td>
</tr>
</table> 
  </html>
@@ b.html.ep
  <!DOCTYPE html>
  <html>
    <head><title><%= title %></title></head>
    <body><%= content %></body>
 <table border="1">
<tr>
<td>row 1, cell 1</td>
<td>row 1, cell 2</td>
</tr>
<tr>
<td>row 2, cell 1</td>
<td>row 2, cell 2</td>
</tr>
</table> 
  </html>
@@ c.html.ep
  <!DOCTYPE html>
  <html>
    <head><title><%= title %></title></head>
    <body><%= content %></body>
    <table border="1">
<tr>
<td>row 1, cell 1</td>
<td>row 1, cell 2</td>
</tr>
<tr>
<td>row 2, cell 1</td>
<td>row 2, cell 2</td>
</tr>
</table> 
  </html>
本当に感動です
 <table border="1">
    <tr>
    <td>row 1, cell 1</td>
    <td>row 1, cell 2</td>
    </tr>
    <tr>
    <td>row 2, cell 1</td>
    <td>row 2, cell 2</td>
    </tr>
    </table> 
各htmlに追加するのではなく、すべてのhtmlを使用します