Method 1: Using pre-defined Bootstrap classes
Bootstrap has pre-defined classes for changing modal dimension attributes to be used with the div element containing .modal-dialog. These are listed below:
<!-- Small Bootstrap Modal Example --> <!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css"> <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script> <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/js/bootstrap.min.js"></script> </head> <body> <div class="container-fluid"> <h2>Small Modal</h2> <p>Other classes mentioned above are also implemented in the same manner.</p> <button type="button" class="btn btn-success" data-toggle="modal" data-target="#modal"> Open Small-modal </button> <!-- Modal Code --> <div class="modal fade" id="modal" role="dialog"> <div class="modal-dialog modal-sm"> <!-- .modal-sm here makes a small modal Can be replaced with '.modal-md' & '.modal-lg' --> <div class="modal-content"> <div class="modal-header"> <button type="button" class="close" data-dismiss="modal">×</button> <h4 class="modal-title">Bajarangi Soft</h4> </div> <div class="modal-body"> <p>Bajarangi Soft- A computer code portal</p> </div> <div class="modal-footer"> <button type="button" class="btn btn-default" data-dismiss="modal">Close</button> </div> </div> </div> </div> </div> </body> </html>
<!-- Changing CSS properties for the div containing '.modal-dialog' class --> <!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="stylesheet"href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css"> <script src= "https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"> </script> <script src= "https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/js/bootstrap.min.js"> </script> <style> .custom { width: 600px; min-height: 400px; } </style> </head> <body> <div class="container-fluid"> <h2>Custom-sized Modal</h2> <p>We are changing CSS properties of div containing the '.modal-dialog' to do the same.</p> <button type="button" class="btn btn-success" data-toggle="modal" data-target="#modal"> Open Custom-sized modal </button> <!-- Modal Code --> <div class="modal fade" id="modal" role="dialog"> <div class="modal-dialog"> <!-- '.custom' class added here to do the same --> <div class="modal-content custom"> <div class="modal-header"> <button type="button" class="close" data-dismiss="modal"> × </button> <h4 class="modal-title"> Bajarangi Soft </h4> </div> <div class="modal-body"> <p>Bajarangi Soft - It is a web Designing Portal</p> </div> </div> </div> </div> </div> </body> </html>