Correggendo gli apici, mettendo la N a "transparent" ed inserendo il "punto e virgola" questi sono gli errori che ho ottenuto (sono aumentati):

Line : 3 font-family: You are encouraged to offer a generic family as a last alternative
Line : 3 (Level : 1) Family names containing whitespace should be quoted. If quoting is omitted, any whitespace characters before and after the name are ignored and any sequence of whitespace characters inside the name is converted to a single space. : .testo
Line : 3 (Level : 2) font-family: You are encouraged to offer a generic family as a last alternative : .testo
Line : 9 font-family: You are encouraged to offer a generic family as a last alternative
Line : 9 (Level : 1) Family names containing whitespace should be quoted. If quoting is omitted, any whitespace characters before and after the name are ignored and any sequence of whitespace characters inside the name is converted to a single space. : .menu
Line : 9 (Level : 2) font-family: You are encouraged to offer a generic family as a last alternative : .menu
Line : 12 (Level : 1) You have no background-color with your color : .menu
Line : 17 font-family: You are encouraged to offer a generic family as a last alternative
Line : 17 (Level : 1) Family names containing whitespace should be quoted. If quoting is omitted, any whitespace characters before and after the name are ignored and any sequence of whitespace characters inside the name is converted to a single space. : .intro
Line : 17 (Level : 2) font-family: You are encouraged to offer a generic family as a last alternative : .intro
Line : 23 font-family: You are encouraged to offer a generic family as a last alternative
Line : 23 (Level : 1) Family names containing whitespace should be quoted. If quoting is omitted, any whitespace characters before and after the name are ignored and any sequence of whitespace characters inside the name is converted to a single space. : .copyright
Line : 23 (Level : 2) font-family: You are encouraged to offer a generic family as a last alternative : .copyright
Line : 30 (Level : 1) You have no background-color with your color : A:link
Questo è il CSS corretto:

testo {
font-family : Verdana, Arial, 'Times New Roman', Sans Serif;
font-size : 12px;
}
.menu {
font-family : 'Trebuchet MS', 'Times New Roman', Arial, Sans Serif;
font-size : 14px;
font-weight : bold;
color : #ffffff;
}
.intro {
font-family : Garamond, 'Book Antiqua', Arial, Sans Serif;
font-size : 26px;
}
.copyright {
font-family : Verdana, Arial, Sans Serif;
font-size : 10px;
color : #808080;
}
A:link {
text-decoration : none;
}
A:link {
color : #800000;
background : transparent;
}
A:hover {
border-bottom : 1px dotted #800000;
}
A:visited {
color : #404040;
}
A:visited {
text-decoration : none;
}
Che fare?