如果没有JavaScript，如何选择多个按钮？

<form action="submit-page.html" method="post">
  <label><input type="checkbox" name="option1" value="1"> 选项1</label>
  <label><input type="checkbox" name="option2" value="2"> 选项2</label>
  <label><input type="checkbox" name="option3" value="3"> 选项3</label>
  <!-- 其他按钮... -->
  
  <input type="submit" value="提交">
</form>

<style>
  .selected {
    background-color: yellow;
    color: black;
  }
</style>

<input type="button" value="按钮1" onclick="toggleButton(this)">
<input type="button" value="按钮2" onclick="toggleButton(this)">
<input type="button" value="按钮3" onclick="toggleButton(this)">

<script>
  function toggleButton(button) {
    button.classList.toggle('selected');
  }
</script>

<?php
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
  if (isset($_POST['option1'])) {
    // 选项1被选择
  }
  if (isset($_POST['option2'])) {
    // 选项2被选择
  }
  if (isset($_POST['option3'])) {
    // 选项3被选择
  }
  // 处理其他按钮...
}
?>

<form action="" method="post">
  <label><input type="checkbox" name="option1" value="1"> 选项1</label>
  <label><input type="checkbox" name="option2" value="2"> 选项2</label>
  <label><input type="checkbox" name="option3" value="3"> 选项3</label>
  <!-- 其他按钮... -->
  
  <input type="submit" value="提交">
</form>