[Theme: Twenty Eleven] Menu Shadow

These are the default values.
You can change the rgba values (the part between parentheses) for different colors.You can play with rgba colors here.
The px values affect the size, depth & spread of the shadow.
You can play with those values here.

#access {
-webkit-box-shadow: rgba(0, 0, 0, 0.4) 0px 1px 2px;
-moz-box-shadow: rgba(0, 0, 0, 0.4) 0px 1px 2px;
box-shadow: rgba(0, 0, 0, 0.4) 0px 1px 2px;
}

To remove completely replace the rgba & px values with the word none.

#access {
box-shadow: none;
}