[Solved] CSS Validation

[brown monkey]

I validated my CSS but got this Warning message

Line : 0 font-family: You are encouraged to offer a generic family as a last alternative

What does this mean? I'm new on this thing. Thanks for any replies. BTW, here's my CSS

body{
    font:11pt times;
    margin-left:50px;
    margin-right:50px;
}
pre,tt{
    font:9pt courier new;
}
td{
    vertical-align:top;
    padding:3px;
}
.black{
    color:black;
}
.bordered{
    border:1px solid #c7c7c7;
}
.console{
    padding:3px;
    color:#c7c7c7;
    background:black;
}
.none{
    text-decoration:none;
}
.none:hover{
    text-decoration:underline;
}
.snippet{
    padding:3px;
    background:#efefef;
    border:1px solid #c7c7c7;
}
.wide{
    width:100%;
}