Changing Style Sheet Dynamically

Cascading Style Sheets or CSS allow you to easily control the layout and look of your page. CSS tags or properties are easy to use and affect the look and feel or style of your pages. In this article I am posting code about applying style sheets dynamically in an ASP.Net web application.

--- .Css Pages---

DayAndNight.css

Body {font-family:Arial, Verdana, sans-serif; font-size: 5px; color: #000000;}

{

/* your styles come here*/

}

Site.CSS

Body {font-family:Arial, Verdana, sans-serif; font-size: 5px; color: #000000;}

{

/* your styles come here*/

}

--- .aspx of master page---

Assigned runat ="server" property to access from server side.

In dropdown add styles sheet as a list item.

<asp:DropDownList ID="ddlStyles" runat="server" AutoPostBack="True" onselectedindexchanged="ddlStyles_SelectedIndexChanged">
<asp:ListItem Text="Original" Value="Styles/Site.css"></asp:ListItem>
<asp:ListItem Text="Day And Night" Value="Styles/DayAndNight.css"></asp:ListItem>
</asp:DropDownList>

--- .cs of master page ---

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
if (Session["Theme"] != null)
lnkStyleSheet.Href = Session["Theme"].ToString().Trim();

else
lnkStyleSheet.Href = ddlStyles.SelectedValue.Trim();

if (Session["SelectedIndex"] != null)
{
ddlStyles.SelectedIndex = Convert.ToInt32(Session["SelectedIndex"].ToString());
}

}
}

protected void ddlStyles_SelectedIndexChanged(object sender, EventArgs e)
{
lnkStyleSheet.Href = ddlStyles.SelectedValue.Trim(); // assigning style to link href in aspx page
Session["Theme"] = ddlStyles.SelectedValue.Trim(); // storing selected value in session to maintain across the tabs
Session["SelectedIndex"] = ddlStyles.SelectedIndex; // storing dropdown selected value in session to maintain across the tabs
}

Output

Original Style

Day and night Style

Please give me your comments and advice on this article.
Thanks,
Srinivas Kotra.