Here I will explain how change the appearance of ajax calendar using CSS Styles.
In so many situations I have used calendar control but I didn’t tried to change CSS style of calendar control in one project I got requirement like to match calendar control style to project default colors at that time I changed calendar control style by using following CSS style classes.
First add Ajax tollkit reference to your project and register that ajax referece like this in your aspx page
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="ajaxToolkit" %>
After that design your aspx like this