参数A和C具有无效输入，但只有C突出显示。有没有办法确保参数A也可以？
<html>
<head>
<style type='text/css'>
body, input, select {
font-family: "Segoe UI", sans-serif;
}
span.field {
display: block;
position: relative;
}
form {
width: 500px;
display: inline-block;
}
input:invalid, fieldset:disabled input:invalid {
border: 3px solid red;
}
fieldset:disabled {
background-color: #cccccc;
}
</style>
</head>
<body>
<form>
<fieldset name="a" disabled="">
<legend>Disabled elements</legend>
<span class="field">
<label for="A" >Parameter A</label>
<input name="A" type="number" required="" min="0" step="any" value="-3"> <span class="units">s</span>
</span>
<span class="field">
<label for="B" >Parameter B</label>
<input name="B" type="number" required="" min="0" step="any" value="3"> <span class="units">s</span>
</span>
</fieldset>
<fieldset name="b" >
<legend>Enabled elements</legend>
<span class="field">
<label for="C" >Parameter C</label>
<input name="C" type="number" required="" min="0" step="any" value="-3"> <span class="units">s</span>
</span>
<span class="field">
<label for="D" >Parameter D</label>
<input name="D" type="number" required="" min="0" step="any" value="3"> <span class="units">s</span>
</span>
</fieldset>
</form>
</body>
</html>你的代码运行正常。禁用时，表单字段不应用验证CSS规则，因为它们无法修改，因此没有意义。启用该字段集后，您将看到应用的正确样式。