Position Fixed

[river]

Aqui el archivo css:

<style>
* html body {
overflow:hidden;
}
#Fija {
position:absolute;
top:0;
left:0;
}
html>body #Fija {
position:fixed;
}
#Todo {
position:absolute;
padding-top : 0px;
padding-bottom : 30px;
padding-left : 170px;
padding-right : 5%;
width:100%;
height:100%;
overflow:auto;
text-align: justify;
}
html>body #Todo {
position:static;
top:auto;
left:auto;
width:auto;
height:auto;
overflow:visible;
}
#todo h1 {
font-size: 120%;
font-weight: normal;
color: #000000;
background-color : transparent;
}

#todo h2 {
font-size: 100%;
font-weight: bold;
color: #000000;
background-color : transparent;
}

#todo h4 {
font-size: 75%;
font-weight: bold;
color: #000000;
background-color : transparent;
text-align: center;
line-height: 3px;
}

#todo p{
font-size: 80%;
font-weight: normal;
color: #000000;
background-color : transparent;
line-height : 140%;
}

#menu{
position: absolute;
top : 68px;
left : 2px;
width : 140px;
font-weight: bold;
margin-bottom: 0px;
background-color: #e6c9c1;
line-height: 20px;
}

#menu a{
display: block;
width: 165px;
text-align: left;
text-decoration: none;
font-family: sans-serif;
font-size:12px;
line-height: 20px;
color: #000000;
border: solid 0px #000000;
}

#menu a:hover {
font-size: 12px; COLOR: #44370f; font-weight: bold; text-decoration: none;
background-color:#F7ECEA;
}

</style>