function Somma() {
  document.getElementById("numero2").style.background = "skyblue";
  if (isNaN(parseInt(document.getElementById("numero1").value)) || isNaN(parseInt(document.getElementById("numero2").value))) {
    document.getElementById("output").value = "Errore";
    document.getElementById("output").style.background = "red";
  }
  
  else {
    document.getElementById("output").value = parseInt(document.getElementById("numero1").value) + parseInt(document.getElementById("numero2").value);
    document.getElementById("output").style.background = "lightgreen";
  }
}

function Differenza() {
  document.getElementById("numero2").style.background = "skyblue";
  if (isNaN(parseInt(document.getElementById("numero1").value)) || isNaN(parseInt(document.getElementById("numero2").value))) {
    document.getElementById("output").value = "Errore";
    document.getElementById("output").style.background = "red";
  }
  
  else {
    document.getElementById("output").value = parseInt(document.getElementById("numero1").value) - parseInt(document.getElementById("numero2").value);
    document.getElementById("output").style.background = "lightgreen";
  }
}

function Prodotto() {
  document.getElementById("numero2").style.background = "skyblue";
  if (isNaN(parseInt(document.getElementById("numero1").value)) || isNaN(parseInt(document.getElementById("numero2").value))) {
    document.getElementById("output").value = "Errore";
    document.getElementById("output").style.background = "red";
  }

  else {
    document.getElementById("output").value = parseInt(document.getElementById("numero1").value) * parseInt(document.getElementById("numero2").value);
    document.getElementById("output").style.background = "lightgreen";
  }
}

function Quoziente() {
  document.getElementById("numero2").style.background = "skyblue";
  if (isNaN(parseInt(document.getElementById("numero1").value)) || isNaN(parseInt(document.getElementById("numero2").value))) {
    document.getElementById("output").value = "Errore";
    document.getElementById("output").style.background = "red";
  }

  else if (parseInt(document.getElementById("numero2").value) == 0) {
    document.getElementById("output").value = "Errore";
    document.getElementById("output").style.background = "red";
    document.getElementById("numero2").style.background = "red";
  }
    
  else {
    document.getElementById("output").value = parseInt(document.getElementById("numero1").value) / parseInt(document.getElementById("numero2").value);
    document.getElementById("output").style.background = "lightgreen";
  }
}