带Tip计算器函数的InnerHTML问题

// HTML代码
<div>
  <label for="billAmount">账单金额：</label>
  <input type="number" id="billAmount" />
</div>
<div>
  <label for="tipPercentage">小费百分比：</label>
  <input type="number" id="tipPercentage" />
</div>
<button onclick="calculateTip()">计算小费</button>
<div id="tipAmount"></div>

// JavaScript代码
function calculateTip() {
  var billAmount = document.getElementById("billAmount").value;
  var tipPercentage = document.getElementById("tipPercentage").value;
  
  var tipAmount = billAmount * (tipPercentage / 100);
  var totalAmount = parseFloat(billAmount) + tipAmount;
  
  document.getElementById("tipAmount").innerHTML = "小费金额：" + tipAmount.toFixed(2) + "元<br>总金额：" + totalAmount.toFixed(2) + "元";
}