body
{ 
background: #D8D8D8;
margin:0;
padding:0;
}

nav
{
list-style: none;
padding: 0;
margin: 0;
float:left;
width:100%;
background: #FFFFFF;
}

nav li
{
float: left;
}

nav li a
{
height: 63px;
text-align: center;
font-weight: bold;
font-size: 110%;
display: block;
color:#000000;
padding-left: 0.2em;
padding-right: 0.2em;
text-decoration: none;
}

nav img
{
border: none;
width: 58px;
}

#welcome
{
padding-left: 1em;
padding-right: 1em;
line-height: 3em;
}

#subject
{
text-align: center;
font-weight: bold;
font-size: 130%;
}

#lesson_name
{
text-align: center;
font-weight: bold;
font-size: 150%;
padding: 0.8em;
}

#welcome_refs
{
text-align: center;
font-weight: bold;
font-size: 150%;
width: 50%;
float: left;
}

#tutorial_link
{
width: 50%;
float: left;
}

#tutorial_link img
{
padding: 2em;

}

#exercise_link
{
width: 50%;
float: left;
}

#exercise_link img
{
padding: 2em;
}

#lesson
{
width:800px;
background: #BDBDBD;
}

#welcome_logo img
{
padding: 2em;
}

img
{
border: none;
}

nav a:hover {
text-decoration: underline;
outline-width:1px;
outline-style:solid;
}

nav a.selected {
text-decoration: underline;
background: #BDBDBD;
}

.centeredImage
{
text-align:center;
margin-top:0px;
margin-bottom:0px;
padding:0px;
}

.icon_right
{
float: right;
}