.form-check-input {
  background-color: #e9ecef; /* or #ced4da for darker fill */
  border-color: #ced4da;
  accent-color: #6c757d;
}
.form-check-input:checked { background-color: #6c757d; border-color: #6c757d; }
.form-check-input:focus { border-color: #ced4da; box-shadow: none; }