I just found out! The problem was the widget with a form in it!
This is the code of the form:
Code:
<img src="http://kteis.com/wp-content/uploads/2011/02/KteisBelfry.png" alt="" />
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-CA" lang="en-CA">
<head>
<title>[CSS] Customize your form with CSS - part 1</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<style type="text/css">
<!--
input
{
color: #A9A9A9;
background: #000000;
border: 2px solid #1F1F1F
}
.submit input
{
color: #000;
background: #ffa20f;
border: 2px outset #d7b9c9
width: 100px;}
</style>
</head>
<body>
<form action='http://madmimi.com/signups/subscribe/21647' method='post'>
<div><center><label for='signup_email'><center>email</center></label><br /><input id='signup_email' name='signup[email]' type='text' /><br /><input name='commit' class='button' type='submit' value='sign up' <p><center>for newsletter</center></p></center>
</div>
</form>
</body>
</html>
Oh, this is relieving!
EDIT:
I removed the styling and now it is ok in all browsers.