javascript - 无法更改 div 标记中段落的 css 属性

Question

我想创建一个函数来更改 div 标签中段落的字体大小和文本对齐属性，该标签在按下按钮时执行。

function acknowledge()
{
  document.getElementById('centretext').innerHTML = "";
  document.getElementById('button1').style.display = "none";
  document.getElementById('centretext').style.font-size = "99%";
  document.getElementById('centretext').style.text-align = "left";
}

它的原始属性是:

#centretext
{
  font-size: 200%;
  font-family: Merriweather;
  text-align: center;
  font-weight:bolder;
}

然而当按钮被点击时，没有任何反应。如果我删除函数的最后两行(即更改属性的行)，那么前两行可以正常执行。我究竟做错了什么？ 编辑:div:

<div id = "centre">
      <p id="centretext">
        You are a cell.
        <br>
        It's the survival of the fittest.
        <br>
        <br>
        To survive, you must divide, grow and evolve.
      </p>

      <p id="centretext2">
      </p>

      <button class ="buttonformat" id="button1" type="button" onclick="acknowledge()"> OK </button>
      </div>

Answer 1

    document.getElementById('centretext').style.fontSize = "99%";
    document.getElementById('centretext').style.textAlign = "left";