Comment griser le champs de mon bouton pop up

<!-- HTML -->
<label><input type="radio" class="choix-button" name="choix-button" value="Modification"> Modification</label>
<label><input type="radio" class="choix-button" name="choix-button" value="Création"> Création</label>
<label><input type="radio" class="choix-button" name="choix-button" value="Consultation"> Consultation</label>

<button class="btn btn-modification">Modification</button>
<button class="btn btn-creation">Création</button>
<button class="btn btn-consultation">Consultation</button>

/* JAVASCRIPT */
var radios = document.querySelectorAll(".choix-button");

for (var i = 0; i < radios.length; i++) {
	radios[i].addEventListener("click", function() {
    var valueRadio = this.value;
    
    if (valueRadio == 'Consultation') {
    	document.querySelectorAll('.btn-modification')[0].disabled = true;
      document.querySelectorAll('.btn-creation')[0].disabled = true;
    }
  }); 
}