I add this code to my website in asp.net.

Refer

http://www.w3schools.com/aspnet/prop_webcontrol_style_cssclass.asp

http://dotnetguts.blogspot.in/2007/09/applying-css-to-aspnet-application.html

Applying CSS to asp.net web application

• Applying CSS is easy
• Create a .CSS File in notepad or you can use CSS Editor available with VS.Net

Let say i have create .CSS File and placed it in folder "CSS"

Create Sample .CSS File named "MyCSS.CSS" you can choose suitable name for .CSS File

Step1: Adding .CSS File to Web application


Now copy and paste the .CSS Content, example

To apply to following style to all Paragraph Tag.
p
{
color:Red;
font-size:x-large;
font-family:Verdana;
background-color:Gray;
}

To apply to following style to all Heading1 Tag.
h1
{
color:Blue;
background-color:Yellow;
font-family:Comic Sans MS;
}

Let say, I want to apply a specific style to Paragraph Tag to some Page3 in my Web Application, you can do this using "class" attribute of Paragraph Tag, here you need to apply

.
.pForMyPage3
{
color:Gray;
font-size:x-large;
font-family:Verdana;
background-color:Red;
}

Similarly i have used same for button control.
.ButtonControl
{
background-color:Red;
color:Yellow;
}



Step2: Adding content to .CSS File




Step 3: Adding .CSS File Link into .aspx Page

See figure for knowing how to apply CSS to control and adding link tag.