css按钮样式未应用

Question

我正在尝试使用以下CSS设置按钮样式：

div.browse input {
    -moz-box-shadow:inset 0px 1px 0px 0px #ffffff;
    -webkit-box-shadow:inset 0px 1px 0px 0px #ffffff;
    box-shadow:inset 0px 1px 0px 0px #ffffff;
    background:-webkit-gradient(linear, left top, left bottom, color-stop(0.05, #f9f9f9), color-stop(1, #e9e9e9));
    background:-moz-linear-gradient(top, #f9f9f9 5%, #e9e9e9 100%);
    background:-webkit-linear-gradient(top, #f9f9f9 5%, #e9e9e9 100%);
    background:-o-linear-gradient(top, #f9f9f9 5%, #e9e9e9 100%);
    background:-ms-linear-gradient(top, #f9f9f9 5%, #e9e9e9 100%);
    background:linear-gradient(to bottom, #f9f9f9 5%, #e9e9e9 100%);
    filter:progid:DXImageTransform.Microsoft.gradient(startColorstr='#f9f9f9', endColorstr='#e9e9e9',GradientType=0);
    background-color:#f9f9f9;
    -moz-border-radius:6px;
    -webkit-border-radius:6px;
    border-radius:6px;
    border:1px solid #dcdcdc;
    display:inline-block;
    cursor:pointer;
    color:#666666;
    font-family:arial;
    font-size:13px;
    font-weight:bold;
    padding:8px 63px;
    text-decoration:none;
    text-shadow:0px 1px 0px #ffffff;
}div.browse input:hover {
    background:-webkit-gradient(linear, left top, left bottom, color-stop(0.05, #e9e9e9), color-stop(1, #f9f9f9));
    background:-moz-linear-gradient(top, #e9e9e9 5%, #f9f9f9 100%);
    background:-webkit-linear-gradient(top, #e9e9e9 5%, #f9f9f9 100%);
    background:-o-linear-gradient(top, #e9e9e9 5%, #f9f9f9 100%);
    background:-ms-linear-gradient(top, #e9e9e9 5%, #f9f9f9 100%);
    background:linear-gradient(to bottom, #e9e9e9 5%, #f9f9f9 100%);
    filter:progid:DXImageTransform.Microsoft.gradient(startColorstr='#e9e9e9', endColorstr='#f9f9f9',GradientType=0);
    background-color:#e9e9e9;
}div.browse input:active {
    position:relative;
    top:1px;
}

html代码：

<div class="browse">
    <input name="UPLOAD_MAX_FILESIZE" value="45971520"  type="hidden"/>
    <input type="file" name="file" id="file" />

谁能告诉我它为什么不起作用？