.btn-close {
  filter: var(--bs-btn-close-white-filter);
  --bs-btn-close-white-filter: invert(1) grayscale(100%) brightness(200%);
}

.modal {
  --bs-modal-color: #adb5bd;
  --bs-modal-bg: #212529;
  --bs-modal-border-color: rgba(255,255,255,0.15);
  --bs-modal-header-border-color: #495057;
  --bs-modal-footer-border-color: #495057;
}

.btn-close {
  --bs-btn-close-white-filter: invert(1) grayscale(100%) brightness(200%);
  filter: var(--bs-btn-close-white-filter);
}