How to define input type=file style

<input type="file" name="file" />

<div class="file-box">
<form action="" method="post" enctype="multipart/form-data">
<input type='text' name='textfield' id='textfield' class='txt' />
<input type='button' class='btn' value='Browse...' />
<input type="file" name="fileField" class="file" id="fileField" size="28" onchange="document.getElementById('textfield').value=this.value" />
<input type="submit" name="submit" class="btn" value="Upload" />
</form>
</div>

.file-box{ position:relative;width:340px}
.txt{ height:22px; border:1px solid #cdcdcd; width:180px;}
.btn{ background-color:#FFF; border:1px solid #CDCDCD; height:24px; width:70px;}
.file{ position:absolute; top:0; right:80px; height:24px; filter:alpha(opacity:0);opacity: 0;width:260px }