css设置字体大小失效

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>CSS Font Size Example</title>
    <style>
        .parent {
            font-size: 16px;
        }
        .child {
            font-size: 20px; /* 确保这个值没有被其他样式覆盖 */
        }
        .specific-selector {
            font-size: 20px !important;
        }
        .compatible {
            font-size: 20px;
            -webkit-font-size: 20px; /* Safari 和 Chrome */
            -moz-font-size: 20px; /* Firefox */
        }
    </style>
</head>
<body>
    <div class="parent">
        Parent Text
        <div class="child">
            Child Text
        </div>
    </div>
    <div class="specific-selector">
        Specific Selector Text
    </div>
    <div class="compatible">
        Compatible Text
    </div>
</body>
</html>