document.addEventListener('DOMContentLoaded', function() {
                                          const phoneInput = document.getElementById('phone');
                                          const submitButton = document.querySelector('.loginnn');
                  
                                          function validatePhone(phone) {
                                            // Ensure phone number contains only digits, and is at least 8 digits long
                                            const regex = /^\d{8,18}$/;
                                            return regex.test(phone);
                                          }
                  
                                          function validateForm() {
                                            const phoneValue = phoneInput.value.trim();
                                            const phoneValid = validatePhone(phoneValue);
                  
                                            if (phoneValid) {
                                              submitButton.disabled = false;
                                              submitButton.style.backgroundColor = '#004877'; // Normal color (Bootstrap primary button color)
                                            } else {
                                              submitButton.disabled = true;
                                              submitButton.style.backgroundColor = 'rgb(19, 168, 218)'; // Disabled color
                                            }
                                          }
                  
                                          phoneInput.addEventListener('input', function() {
                                            this.value = this.value.replace(/\D/g, ''); // Removes non-digit characters
                                            validateForm();
                                          });
                  
                                          // Initial validation check
                                          validateForm();
                                        });