html, body {
  margin: 0;
  padding: 0;
}
body {
  font-family: "Noto Sans JP", "Hiragino Sans", "Yu Gothic", Meiryo, sans-serif;
  line-height: 1.9;
  letter-spacing: 0.02em;
}
h1, h2, h3, h4, h5, h6, p {
  margin: 0;
}
ul {
  margin: 0;
  padding: 0;
  list-style: none;
}
ol {
  border-block: 1px solid #eee;
  margin-block: 2rem;
  padding-block: 1rem;
}
ol li{
  padding-block: 0.5rem;
}
a {
  color: inherit;
  text-decoration: none;
}
a:hover {
  color: #69f;
  text-decoration: underline;
}
textarea {
  width: 100%;
}
button, input, textarea, select  {
  font: inherit;
}
img, video {
  display: block;
  max-width: 100%;
  height: auto;
}

header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1rem;
}
header p {
  margin-top: 1.5rem;
  font-size: 0.7rem;
  line-height: 1rem;
}
header ul {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-left: auto;
  margin-right: 2rem;
}
main {
  width: min(100% - 2rem, 640px);
  margin-inline: auto;
}
footer {
  background: #333;
  color: #fff;
  padding: 30px 0;
  margin-top: 30px;
}
footer a {
  color: #fff;
}
footer ul {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 2rem;
}
footer li + li::before {
  content: "";
  border-left: 1px solid #555;
  margin-right: 2rem;
}

h1 {
  font-size: 1.5rem;
  margin-bottom: 1.5rem;
}
h2 {
  font-size: 1.4rem;
  border-top: 2px solid #ccc;
  margin-top: 2rem;
  padding-top: 1rem;
  margin-bottom: 1.5rem;
}
h3 {
  font-size: 1rem;
  margin-block: 2rem;
}
p {
  margin-bottom: 1.5rem;
}
dl {
  background: #eee;
  padding: 0.5rem 1rem;
}
dt {
  margin-top: 1rem;
  padding-left: 0.5rem;
  border-left: 4px solid #888;
}
dd {
  margin-left: 0.75rem;
  margin-bottom: 1rem;
}
.source {
  margin-block: 2rem;
  padding-block: 1rem;
  border-top: 1px solid #ddd;
  color: #666;
  font-size: 0.8rem;
}