body {
  background-color: #ffffff;
  color: black;
  font-family: Arial, Tahoma, sans-serif;
  margin: 0px;
  border: 0px;
  padding: 0px;
}

h1 {
  font-size: large;
}

h2 {
  font-size: medium;
}

#footer {
    font-size: smaller;
    margin-top: 1em;
}

#navigation {
    font-size: smaller;
    margin-top: 1em;
}

#units {
    font-size: smaller;
    margin-top: 1em;
}

#content .category {
    background-color: #c0c0c0;
    font-weight: bold;
    text-align: left;
}

#content td {
    text-align: center;
}

#units {
    font-size: smaller;
    margin-top: 1em;
}

.error {
    border: 1px solid red;
    background-color: #FFF6BF;
    padding: 2em;
    margin: 2em;
}