:root {
  --content-width: 760px;
}

* {
  box-sizing: border-box;
}

html {
  min-height: 100%;
}

body {
  margin: 0;
  padding: 2.2rem 1.4rem 3.5rem;
  font-family: 'Yu Mincho', 'Hiragino Mincho ProN', 'Hiragino Mincho Pro', serif;
  line-height: 1.85;
  transition: background-color 0.15s ease;
}

.back-link {
  display: block;
  width: min(100%, var(--content-width));
  margin: 0 auto 1.8rem;
  font-size: 0.92rem;
  text-decoration: none;
  color: inherit;
  opacity: 0.72;
}

.back-link:hover {
  opacity: 1;
  text-decoration: underline;
  text-underline-offset: 0.18em;
}

.content {
  width: min(100%, var(--content-width));
  margin: 0 auto;
  font-size: 1.03rem;
  word-break: break-word;
  overflow-wrap: break-word;
}

.content h1 {
  margin: 0 0 2.2rem;
  text-align: center;
  font-size: clamp(1.65rem, 4vw, 2rem);
  font-weight: 500;
  letter-spacing: 0.03em;
}

.content h2 {
  margin: 2.5rem 0 1rem;
  padding-bottom: 0.35rem;
  font-size: 1.25rem;
  font-weight: 500;
  border-bottom: 1px solid currentColor;
}

.content p {
  margin: 1rem 0;
}

.content ul,
.content ol {
  padding-left: 1.6rem;
}

.content li {
  margin: 0.45rem 0;
}

.content a {
  color: inherit;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
}

iframe {
  display: block;
  max-width: 100%;
  margin: 1.5rem auto;
}

/* Default hobby page: neutral and intentionally plain. */
body.light {
  background: #fafafa;
  color: #343434;
}

body.light .content a:hover {
  color: #000;
}

/* Hidden hub: keeps the pale blue nuance of the main site. */
body.hidden {
  background: #eef8fb;
  color: #2f3c40;
}

body.hidden .content h1 {
  color: #284f5c;
}

body.hidden .content h2 {
  color: #326575;
  border-bottom-color: #b8d9e2;
}

body.hidden .content a {
  color: #265f73;
}

body.hidden .content a:hover {
  color: #153f4d;
}

/* Paper comments: warm, simple orange accent without card decoration. */
body.paper {
  background: #fff8ef;
  color: #4b3829;
}

body.paper .content h1 {
  color: #8a4a18;
}

body.paper .content h2 {
  color: #9b551d;
  border-bottom-color: #e5b987;
}

body.paper .content a {
  color: #a75516;
}

body.paper .content a:hover {
  color: #73360d;
}

body.paper .back-link {
  color: #8a4a18;
}

/* Classical music: restrained monochrome, with the contrast of piano keys. */
body.piano {
  background: #f4f4f4;
  color: #1c1c1c;
  border-top: 5px solid #161616;
}

body.piano .content {
  letter-spacing: 0.005em;
}

body.piano .content h1 {
  color: #111;
  padding-bottom: 0.7rem;
  border-bottom: 2px solid #111;
}

body.piano .content h2 {
  color: #111;
  border-bottom-color: #8c8c8c;
}

body.piano .content a {
  color: #202020;
  text-decoration-color: #777;
}

body.piano .content a:hover {
  color: #000;
  text-decoration-color: #000;
}

body.piano .back-link {
  color: #333;
}

/* Backward compatibility with older pages that still say theme: dark. */
body.dark {
  background: #111;
  color: #f4f4f4;
}

@media (max-width: 640px) {
  body {
    padding: 1.5rem 1rem 2.8rem;
  }

  .back-link {
    margin-bottom: 1.3rem;
  }

  .content {
    font-size: 0.98rem;
  }

  .content h1 {
    margin-bottom: 1.7rem;
  }

  .content h2 {
    margin-top: 2rem;
  }
}