looking at your page source this is the top level code generated:
Code:
<link rel="stylesheet" type="text/css" href="includes/templates/tatie/css/style_imagehover.css" />
<link rel="stylesheet" type="text/css" href="includes/templates/tatie/css/stylesheet.css" />
<link rel="stylesheet" type="text/css" href="includes/templates/tatie/css/stylesheet_css_buttons.css" />
<link rel="stylesheet" type="text/css" href="includes/templates/tatie/css/stylesheet_new.css" />

<link rel="stylesheet" type="text/css" href="includes/templates/tatie/css/stylesheet_original.css" />
as you can see you have every style sheet available and being parsed; remove the stylesheet_original and the stylesheet_new form your tatie folder leaving the main stylesheet.css from the template_default set of files. Edit only this file for basic site styling.