.calc-modal-overlay {
  position: fixed;
  inset: 0;
  z-index: 1100;
  background: #0a0a0a;
}

.calc-modal-frame {
  width: 100%;
  height: 100%;
  display: flex;
}

.calc-modal-iframe {
  flex: 1;
  border: none;
  width: 100%;
  height: 100%;
  display: block;
}

/* Bouton retour flottant universel (réutilisable partout) */
.btn-back {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 1200;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: rgba(0,0,0,0.6);
  border: 1px solid rgba(240,235,220,0.2);
  color: rgba(240,235,220,0.9);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: background 0.2s, border-color 0.2s;
  padding: 0;
}
.btn-back:hover {
  background: rgba(0,0,0,0.8);
  border-color: rgba(240,235,220,0.5);
}
.btn-back svg { width: 28px; height: 28px; }