body {
  color: black; background-color: #FFFFFF;
  font-size: 100.00%;
  font-family: Helvetica,Arial,sans-serif;
  margin: 0; padding: 1em;
} 

#centered_content {  
  background-color: #FFFFFF;
  width: 800;
  padding: 10;
  margin-left: auto;
  margin-right: auto;
}

#impressum {  
  width: 800;
  padding: 10;
  margin: 0;
}

#navigation {  
  background-color: #F0F0FF;
}

#teaching_button {
  background-color: #999999;
}

#theses_button {
  background-color: #9999AA;
}

#projects_button {
  background-color: #9999BB;  
}

#research_button {
  background-color: #9999CC;    
}

.button {
  height: 33;
  width: 100;
  font-weight:bold;
  background-color: #9999AA;
  border-style:solid;
  border-width:0px;
  border-color:#6666AA;  
}

.content {
  position: absolute;
  background-color: #FFFFFF;
  visibility: hidden;
  padding: 10;
  width: 800;
  margin-left: auto;
  margin-right: auto;
}

.invis {
  visibility: hidden;  
}