I create a file called test.html with some code

its presence will be :

Now, putting some CSS codes in test.css file:
and its presence:
#menu a, #menu a:visited {
position:relative;
text-decoration:none;
background-color:#F39;
text-align:center;
}

Changing the text colour from blue to white:
color:#fff;and the change is :


Making a block for meu:
display:block;

Editing the block size:
width:10em;

Making border to separate buttons
border:2px solid #fff;


Decorating each button
border-color: #F99;

It now has pink background but can not become buttons so I have some code:
border-color: #FCF #F6C #F6F #FCF;

Extending padding size in each buttons:
padding:0.25em;

Each button is bigger than before.
Removing Light Pink border among different buttons:
margin:0.5em;

Making a hover for each button:
#menu a:hover {
top:2px;
}
When I use a mouse hovering "About Us" button, it is shaked and move down a bit.
If I add a line of CSS code:
left:2px;I will have the hoverd "About Us" button moving to right a bit.

Set the text colour always become White:
color:#fff;At the end, I make border of each button become different:
border-color:#F6C #FCF #FCF #F69;











