* {
  box-sizing: border-box;
}

body {
  max-width: 800px;
  min-width: 300px;
  width: 50vw;
  margin: 10px auto;
  background-color: #f0f0f0;
  color: #333;
}

h1 {
  margin: 0 auto;
  font-size: 115%;
  border-bottom: 2px solid gray;
  text-align: center;
}

h2 {
  margin: 0.5em auto;
  font-size: 100%;
  border-color: #339;
  border-width: 0 0 1px 5px;
  border-style: solid;
  padding: 2px 8px 3px;
}

div.caution {
  margin: 0.5em auto;
  padding: 5px;
  border: 1px solid #f00;
  border-radius: 5px;
  background-color: #ffe0e0;
  font-size: 90%;
}

div.attention {
  margin: 0.5em auto;
  padding: 5px;
  border: 1px solid #c90;
  border-radius: 5px;
  background-color: #ffffe0;
  font-size: 90%;
}

table {
  border-collapse: collapse;
  border: 3px double gray;
  margin: 0.5em auto;
}

thead th {
  font-size: 85%;
  font-weight: normal;
  border-style: solid solid double solid;
  border-color: gray;
  border-width: 1px 1px 3px 1px;
}

tbody th, tbody td {
  padding: 3px 5px;
  border: 1px solid gray;
}

a:link, a:visited {
  color: blue;
}

a:hover, a:active {
  color: red;
}

div.nav {
  font-size: 75%;
  margin: 8px auto;
}

dt {
  font-weight: 600;
  text-decoration: underline;
}

dd {
  margin-bottom: 0.5em;
}

.red {
  color: red;
}

.italic {
  font-style: italic;
}