ASPX PAGE

<p><asp:Label ID="Label3" runat="server" Text="My third Label"></asp:Label></p>

CODE BEHIND

protected void Page_Load(object sender, EventArgs e)
{
// writeing text from code behind
Label2.Text = "Written from code behind";
// Applying CSS style from code behind
Label3.Text = "Written from code behind";
Label3.Font.Bold = true;
string[] fontNames = {"Verdana", "Arial"};
Label3.Font.Names = fontNames;
Label3.Font.Size = FontUnit.Larger;
Label3.ForeColor = System.Drawing.Color.Green;
Label3.BackColor = System.Drawing.Color.Yellow;
}

CSS style can be applied from code behind by accessing the properties of the control with the help of its Id. Most of the CSS styles can be applied using the Font property and its sub properties of the Label control. However you can use ForeColor and BackColor directly from the Label control.

Demo Path: /Label-Literal/LabelPage.aspx