CSS Div Margin "Element Collision Detection" - html

Question

What I need to know is how to make my CSSconfigured for div/element collision detection. Now, I realized that other questions asking for collision detection is kind of the opposite of what I need; to NOT fix it but to create it, and this is what I mean; I need to have, for example, a #altnav element, which is a sidebar, that will continually reach until it hits the #footer element using a min-height: 100% tag. What it currently does is just reach down until 100%, but stops at a certain point in my page (http://www.thehideout.somee.com/games.html to see what I mean). Another example is my #wrap element with a border-left: 2px solid #000000; tag reaches past the #footer element; which I need it to stop at the footer element. So what I'm asking is how can I make the elements detect if it's colliding with another element, and to stop at that element. Priority is key; I would rather have the sidebar with footer fixed first than the #wrap and border tag. Here's the CSS code for the key elements, followed by the whole css incase another #element is causing this.
#wrap {
width: 760px;
margin: auto;
}
#altnav {
margin-top: 35px;
margin-bottom: 10px;
float: right;
width: 190px;
border-left: 2px dashed #000000;
border-bottom: 2px dashed #000000;
min-height: 100%;
background: orange;
}
#altnav p {
color: black;
font-family: terminal;
font-size: 14px;
border-bottom: 1px solid black;
border-top: 1px solid black;
}
#altnav h2 {
text-align: center;
color: black;
font-family: terminal;
font-size: 18px;
}
#body {
padding-top: 50px;
width: 570px;
font-family: Arial, Verdana, Terminal;
font-size: 14px;
}
#footer {
width: 730px;
height: 60px;
clear: both;
font-family: Tahoma, Arial, Terminal, San-Serif;
font-size: 10px;
color: #c9c9c9;
border-top: 1px solid #efefef;
padding: 13px 25px;
line-height: 18px;
}
#footer li {
padding: 0px 2px 0px 2px;
float: right;
display: inline;
text-align: left;
font-family: Terminal, Arial, San-Serif, Tahoma;
font-size: 10px;
}
#footer a {
font-family: Terminal, Arial, San-Serif, Tahoma;
font-size: 10px;
color: #c9c9c9;
text-decoration: none;
}
#footer a:hover {
font-family: Terminal, Arial, San-Serif, Tahoma;
font-size: 10px;
color: red;
text-decoration: underline;
}
#footer #footnav {
display: inline;
width: 310px;
float: right;
text-align: left;
position: relative;
bottom: 65px;
}
Full StyleSheet
html, body {
margin: 0;
padding: 0;
}
.hidden {
display: none;
}
body {
background-position: center;
background-repeat: no-repeat;
font-size: 12px;
color: #666666;
}
#font-face {
font-family: 'karmatic_arcaderegular';
src: url('fonts/ka1-webfont.eot');
src: url('fonts/ka1-webfont.eot?#iefix') format('embedded-opentype'),
url('fonts/ka1-webfont.woff2') format('woff2'),
url('fonts/ka1-webfont.woff') format('woff'),
url('fonts/ka1-webfont.ttf') format('truetype'),
url('fonts/ka1-webfont.svg#karmatic_arcaderegular') format('svg');
font-weight: normal;
font-style: normal;
}
#wrap {
width: 760px;
margin: auto;
}
#header {
height: 60px;
width: auto;
background: #db6d16
url(VexIMG/header.png);
}
#navigation {
width: 760px;
height: 35px;
position: absolute;
border-bottom: 2px solid #000000;
background: orange;
padding: 0px;
}
#navigation .padding {
padding: 2px;
}
#navigation .navlinks {
position: absolute;
top: 1px; left: 0px;
}
#navigation .navlinks ul {
margin: 0px;
padding: 0px;
text-align: center;
list-style-type: none;
width: 760px;
height: 35px;
}
#navigation .navlinks li {
position: relative;
top: 5px;
margin: 0px 5px 0px 5px;
list-style-type: none;
display: inline;
}
#navigation .navlinks li a {
color: #000000;
padding: 5px 0px 9px 0px;
text-decoration: none;
font-size: 18px;
font-family: karmatic_arcaderegular;
padding: 5px 0px 9px 0px;
}
#navigation .navlinks li a:hover {
margin: 0px;
color: #ffffff;
background: orange;
text-decoration: underline;
}
#altnav {
margin-top: 35px;
margin-bottom: 10px;
float: right;
width: 190px;
border-left: 2px dashed #000000;
border-bottom: 2px dashed #000000;
min-height: 100%;
background: orange;
}
#altnav p {
color: black;
font-family: terminal;
font-size: 14px;
border-bottom: 1px solid black;
border-top: 1px solid black;
}
#altnav h2 {
text-align: center;
color: black;
font-family: terminal;
font-size: 18px;
}
#body {
padding-top: 50px;
width: 570px;
font-family: Arial, Verdana, Terminal;
font-size: 14px;
}
#body .secret img {
width: 150px;
height: 100px;
border: 2px solid black;
}
#body .game {
padding: 3px 3px 10px 3px;
}
#body .game img {
align: center;
float: left;
width: 175px;
height: 101px;
border: 2px ridge #ff0000;
}
#body .game caption {
padding-left: 1px;
}
#body .space {
padding-top: 10px;
padding-bottom: 10px;
border-top: 4px ridge red;
border-bottom: 4px ridge red;
}
#body .game caption {
margin-top: 2px;
float: right;
font-family: Terminal, Arial, Verdana, San-Serif;
font-size: 12px;
color: #000000;
border-bottom: 2px dashed #e9e9e9;
}
#body .game a {
font-family: Terminal, Arial, San-Serif, Tahoma;
font-size: 10px;
color: #c9c9c9;
text-decoration: none;
}
#body .game a:hover {
font-family: Terminal, Arial, San-Serif, Tahoma;
font-size: 10px;
color: red;
text-decoration: underline;
}
#footer {
width: 730px;
height: 60px;
clear: both;
font-family: Tahoma, Arial, Terminal, San-Serif;
font-size: 10px;
color: #c9c9c9;
border-top: 1px solid #efefef;
padding: 13px 25px;
line-height: 18px;
}
#footer li {
padding: 0px 2px 0px 2px;
float: right;
display: inline;
text-align: left;
font-family: Terminal, Arial, San-Serif, Tahoma;
font-size: 10px;
}
#footer a {
font-family: Terminal, Arial, San-Serif, Tahoma;
font-size: 10px;
color: #c9c9c9;
text-decoration: none;
}
#footer a:hover {
font-family: Terminal, Arial, San-Serif, Tahoma;
font-size: 10px;
color: red;
text-decoration: underline;
}
#footer #footnav {
display: inline;
width: 310px;
float: right;
text-align: left;
position: relative;
bottom: 65px;
}