100% width minus margin and padding [duplicate]

Answer 1

Another solution is to position the INPUT’s absolute and add left/right props:

#login_box {
    width: 100%;
    position:relative;
}

input[type="text"], input[type="password"] {
    position:absolute;
    left:5px;
    right: 5px
}

You would need to adjust margins etc, since they will be out of the relative layout flow. You can also add padding without trouble, since you didn’t set a fixed width.

This technique is widely supported in all browsers.

Demo: http://jsfiddle.net/wuSDh/3/