html, body{
  font-family: sans-serif;
  color: #ffbb55;
  max-width: 750px;
  margin-left: auto;
  margin-right: auto;
  padding: 5px;
  background: #111;
  }

h1{
 font-style: italic;
 font-size: 4em;
 text-align: center;
 }

.untertitel {
 text-align: center;
}

p{
  max-width: 600px;
}

/*hyperlinks*/
/* unvisited link */
a:link {
  color: #ff7700;
}
/* visited link */
a:visited {
  color: #ff7700;
}
/* mouse over link */
a:hover {
  color: #111;
  background: #f93;
}
/* selected link */
a:active {
  color: #111;
} 

/* collapse section*/
details {
  border: 1px solid #041716;
  border-radius: 2px;
  padding: 0.5em 0.5em 0;
}

summary {
  #font-weight: bold;
  margin: -0.5em -0.5em 0;
  padding: 0.5em;
}

details[open] {
  padding: 0.5em;
}

details[open] summary {
  border-bottom: 1px solid #041716;
  margin-bottom: 0.5em;
}

.topnav {
  overflow: hidden;
  background-color: #ffbb55;
  border-radius: 0.25em;
}

.topnav a {
  float: left;
  color: #111;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
  font-size: 17px;
}

.topnav a:hover {
  background-color: #f93;
  color: #111;
}

#.topnav a.active {
#  background-color: white;
#  color: navy;
#}

/* frame around text */
.main {
  border: 6px double;
  padding: 1em;
}

hr {
  border-color: #ffbb55;
}

/* tables */

table {
  padding: 10px;
}

table.center {
  margin-left: auto; 
  margin-right: auto;
}

th {
  padding-bottom: 20px;
  padding-right: 20px;
  padding-left: 20px;
  border-bottom: 1px solid;
}