* {
  margin: 0;
  padding: 0;
}
html {
  font-size: min(4vw, 32px);
  font-family: sans-serif;
  width: 100%;
  max-width: 1024px;
}
#header > img {
  display: block;
  width: 100%;
}
#header > h1 {
  margin: 0;
  padding: 1em;
  font-size: 1.3em;
  line-height: 1.5em;
}

#contents {
  padding: 1em;
}
#contents hr {
  border-top: 1px dashed #8c8b8b;
  margin: 0.5em;
}
#contents #menu {
  padding: 1em 2em;
  line-height: 2em;
}
#contents .title1 {
  margin-top: 1em;
  font-size: 1.2em;
  font-weight: bold;
}
#contents .title2 {
  margin-top: 0.5em;
  font-weight: bold;
  padding-left: 0.2em;
}
#contents .title3 {
  padding-left: 0.2em;
}
#contents p {
  padding: 0.5em;
}
#contents .page_pic {
  text-align: center;
  padding: 1em;
}
#contents .page_pic a {
  display: inline-block;
  padding: 5px;
  margin: 1em;
  width: fit-content;
  border-radius: 10px;
  box-shadow: 0 3px 10px 0 rgba(0, 0, 0, .5);
  background-color: white;
}
#contents .page_pic a:hover {
  background-color: lemonchiffon;
}
#contents .page_pic img {
  object-fit: contain;
  max-width: 100%;
  height: auto;
  max-height: 260px;
}
#contents .back_to_home {
  margin: 2em 0;
  text-align: center;
}

footer {
  padding: 1rem;
  text-align: center;
}
footer p {
  padding: 0.5rem 0;
}

img {
  max-width: 100%;
}

.youtube {
  width: 100%;
  aspect-ratio: 16 / 9;
}
.youtube iframe {
  width: 100%;
  height: 100%;
}