@charset "UTF-8";

:root {
  --background: #f7f7f5;
  --text: #222222;
  --accent: #dc4813;
  --line: #d8d8d3;
  --subtle: #777777;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--background);
  color: var(--text);
  font-family:
    "Yu Mincho",
    "YuMincho",
    "Hiragino Mincho ProN",
    "Hiragino Mincho Pro",
    serif;
  line-height: 1.9;
}

.site-header,
.site-menu,
.site-footer {
  width: min(880px, calc(100% - 48px));
  margin-right: auto;
  margin-left: auto;
}

.site-header {
  padding-top: 84px;
  padding-bottom: 64px;
}

.site-menu {
  padding-bottom: 80px;
}

.site-header h1 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 500;
  letter-spacing: 0.1em;
  line-height: 1.35;
}

.site-subtitle {
  margin: 10px 0 0;
  font-size: 0.95rem;
  letter-spacing: 0.12em;
}

.update {
  margin: 38px 0 0;
  padding-top: 10px;
  border-top: 1px solid var(--line);
  color: var(--subtle);
  font-size: 0.75rem;
}

.update-item {
  margin: 2px 0;
}

details {
  margin: 0;
}

summary {
  cursor: pointer;
  list-style: none;
}

summary::-webkit-details-marker {
  display: none;
}

.menu-section {
  margin-bottom: 32px;
}

.menu-section > summary {
  display: inline-block;
  font-size: 1.25rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  transition: color 0.18s ease;
}

.menu-section > summary:hover {
  color: var(--accent);
}

.menu-list {
  margin: 8px 0 0 1.5em;
  padding: 0 0 0 1.4em;
  border-left: 1px solid var(--line);
  list-style: none;
}

.menu-list > li {
  margin: 3px 0;
}

.menu-list a {
  color: var(--text);
  text-decoration: none;
  font-size: 0.98rem;
  transition: color 0.18s ease;
}

.menu-list a:hover {
  color: var(--accent);
}

.sub-section {
  margin: 3px 0;
}

.sub-section > summary {
  display: inline-block;
  color: var(--text);
  font-size: 0.98rem;
  transition: color 0.18s ease;
}

.sub-section > summary:hover {
  color: var(--accent);
}

.sub-section > ul {
  margin: 1px 0 4px 1.5em;
  padding: 0;
  list-style: none;
}

.sub-section > ul li {
  margin: 1px 0;
}

.sub-section > ul a {
  color: var(--text);
  text-decoration: none;
  font-size: 0.9rem;
  transition: color 0.18s ease;
}

.sub-section > ul a:hover {
  color: var(--accent);
}

.note {
  font-size: 0.82em;
  color: var(--subtle);
}

.site-footer {
  padding-top: 18px;
  padding-bottom: 50px;
  border-top: 1px solid var(--line);
  color: var(--subtle);
  font-size: 0.72rem;
}

@media (max-width: 600px) {
  .site-header,
  .site-menu,
  .site-footer {
    width: calc(100% - 32px);
  }

  .site-header {
    padding-top: 48px;
    padding-bottom: 48px;
  }

  .menu-section > summary {
    font-size: 1.15rem;
  }

  .menu-list {
    margin-left: 0.8em;
    padding-left: 1em;
  }
}