工作需要筆記

<form action="" method="post" enctype="multipart/form-data">
    <div class="upload">
        <input type="file" name="upload"/>
    </div>
</form>

div.upload {
    width: 157px;
    height: 57px;
    background: url(https://lh6.googleusercontent.com/-dqTIJRTqEAQ/UJaofTQm3hI/AAAAAAAABHo/w7ruR1SOIsA/s157/upload.png);
    overflow: hidden;
}

div.upload input {
    display: block !important;
    width: 157px !important;
    height: 57px !important;
    opacity: 0 !important;
    overflow: hidden !important;
}

http://jsfiddle.net/gabrieleromanato/mxq9R/