JS & CSS: Rollover text on URL issue

The code below uses css and js to present text to the user when they roll over a URL but if you test the code you will see that the text automatically gets outputted to the user when the page loads. How can i prevent that?



<style type="text/css">
sub1 {

display: none;
}
<style type="text/css">
sub2 {

display: none;
}

</style>
<script language="JavaScript">
function setVisibility(id, visibility) {
document.all[id].style.display = visibility;
}

</script>
<body >
<a href='tutorial.php' onMouseOver="setVisibility('sub1', 'inline');" onMouseOut="setVisibility('sub1','none');">Tutorial Page</a><br>
<a href='logout.php' onMouseOver="setVisibility('sub2', 'inline');" onMouseOut="setVisibility('sub2','none');">Logout</a><br>
<div id="sub1">Do you want to learn how to use the system i have spent ages writing? Then watch the tutorial and learn something</div>
<div id="sub2">Do you want tfdasfdsafd</div>