*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #fafaf8;
  --surface: #ffffff;
  --border: #e8e4dc;
  --text: #1a1a1a;
  --muted: #888;
  --accent: #2d5a27;
  --accent-light: #f0f4ef;
  --font: 'Hiragino Kaku Gothic ProN', 'Hiragino Sans', 'Noto Sans JP', sans-serif;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.9;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* Layout */
.site-header {
  border-bottom: 1px solid var(--border);
  padding: 20px 0;
  background: var(--surface);
}
.site-header .inner {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.site-title {
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.05em;
  color: var(--text);
}
.site-title a { color: var(--text); }
.site-nav { font-size: 13px; color: var(--muted); }

main {
  max-width: 720px;
  margin: 0 auto;
  padding: 48px 24px 80px;
}

/* Index */
.page-heading {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 32px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
}

.article-list { list-style: none; }
.article-list li {
  padding: 20px 0;
  border-bottom: 1px solid var(--border);
}
.article-list li:last-child { border-bottom: none; }

.article-meta {
  font-size: 12px;
  color: var(--muted);
  margin-bottom: 6px;
}
.article-title {
  font-size: 18px;
  font-weight: 700;
  line-height: 1.5;
  margin-bottom: 8px;
}
.article-title a { color: var(--text); }
.article-title a:hover { color: var(--accent); text-decoration: none; }
.article-excerpt {
  font-size: 14px;
  color: #555;
  line-height: 1.7;
}

/* Article */
.article-header {
  margin-bottom: 40px;
  padding-bottom: 32px;
  border-bottom: 1px solid var(--border);
}
.article-header .meta {
  font-size: 12px;
  color: var(--muted);
  margin-bottom: 12px;
}
.article-header h1 {
  font-size: 26px;
  font-weight: 700;
  line-height: 1.4;
}

.article-body { font-size: 16px; line-height: 2; }
.article-body h2 {
  font-size: 18px;
  font-weight: 700;
  margin: 40px 0 16px;
  padding-left: 12px;
  border-left: 3px solid var(--accent);
}
.article-body p { margin-bottom: 20px; }
.article-body strong { font-weight: 700; }

.article-footer {
  margin-top: 56px;
  padding-top: 24px;
  border-top: 1px solid var(--border);
  font-size: 13px;
  color: var(--muted);
}
.article-footer a { color: var(--accent); }

/* Research box */
.research-box {
  background: var(--accent-light);
  border: 1px solid #c8dcc5;
  border-radius: 6px;
  padding: 24px 28px;
  margin: 40px 0;
  font-size: 14px;
}
.research-box h3 {
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 16px;
}
.research-box .framework {
  font-weight: 700;
  margin-bottom: 4px;
  font-size: 15px;
}
.research-box .framework-detail {
  color: #444;
  margin-bottom: 16px;
  line-height: 1.7;
}

/* Back link */
.back-link {
  display: inline-block;
  margin-bottom: 32px;
  font-size: 13px;
  color: var(--muted);
}
.back-link:hover { color: var(--accent); text-decoration: none; }

@media (max-width: 600px) {
  main { padding: 32px 16px 60px; }
  .site-header .inner { padding: 0 16px; }
  .article-header h1 { font-size: 22px; }
}