:root {
  --navy: #1a2744;
  --navy2: #26375e;
  --accent: #2f6df0;
  --accent-d: #1f51c4;
  --ink: #1a2230;
  --muted: #6b7689;
  --line: #e6e9f0;
  --bg: #f6f8fc;
  --card: #ffffff;
  --radius: 16px;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--bg);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Kaku Gothic ProN", "Hiragino Sans", "Noto Sans JP", "Yu Gothic UI", Meiryo, sans-serif;
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}

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

.wrap { max-width: 760px; margin: 0 auto; padding: 0 20px; }
.wrap-wide { max-width: 1080px; margin: 0 auto; padding: 0 20px; }

/* header */
header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(246, 248, 252, 0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 900;
  color: var(--navy);
  font-size: 16px;
  text-decoration: none;
}

.brand:hover { text-decoration: none; }
.brand img { height: 32px; width: auto; }

.nav-links {
  display: flex;
  gap: 20px;
  font-size: 14px;
  font-weight: 600;
  color: var(--muted);
}

.nav-links a { color: var(--muted); text-decoration: none; }
.nav-links a:hover { color: var(--ink); }

/* breadcrumb */
.breadcrumb {
  font-size: 13px;
  color: var(--muted);
  padding: 16px 0 0;
}

.breadcrumb ol {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
}

.breadcrumb li::after { content: "›"; margin: 0 6px; color: var(--line); }
.breadcrumb li:last-child::after { content: ""; margin: 0; }
.breadcrumb a { color: var(--muted); }

/* article */
.article-header { padding: 32px 0 24px; }

.article-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 13px;
  color: var(--muted);
  margin-bottom: 16px;
}

.category-badge {
  display: inline-block;
  background: #eaf0ff;
  color: var(--accent-d);
  font-weight: 700;
  font-size: 12px;
  padding: 4px 10px;
  border-radius: 999px;
}

.article-header h1 {
  font-size: 28px;
  line-height: 1.4;
  color: var(--navy);
  margin: 0 0 16px;
  letter-spacing: 0.01em;
}

.article-body {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 32px 28px;
  margin-bottom: 32px;
}

.article-body h2 {
  font-size: 22px;
  color: var(--navy);
  margin: 36px 0 16px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--line);
}

.article-body h2:first-child { margin-top: 0; }

.article-body h3 {
  font-size: 17px;
  color: var(--navy2);
  margin: 24px 0 12px;
}

.article-body p { margin: 0 0 16px; }

.article-body ul, .article-body ol {
  margin: 0 0 16px;
  padding-left: 1.4em;
}

.article-body li { margin-bottom: 6px; }

.article-body strong { color: var(--navy); }

/* CTA */
.cta-box {
  background: linear-gradient(135deg, var(--navy) 0%, var(--navy2) 100%);
  color: #fff;
  border-radius: var(--radius);
  padding: 28px 24px;
  margin-bottom: 32px;
  line-height: 1.8;
}

.cta-box p { margin: 0 0 12px; }
.cta-box p:last-child { margin: 0; }
.cta-box a { color: #a8c4ff; font-weight: 700; }

/* related */
.related { margin-bottom: 48px; }
.related h2 { font-size: 18px; color: var(--navy); margin: 0 0 16px; }

.related-list { list-style: none; margin: 0; padding: 0; }

.related-list li {
  border-bottom: 1px solid var(--line);
  padding: 14px 0;
}

.related-list a {
  color: var(--ink);
  font-weight: 600;
  text-decoration: none;
}

.related-list a:hover { color: var(--accent); }
.related-list .date { font-size: 12px; color: var(--muted); margin-top: 4px; }

/* blog index */
.page-title {
  font-size: 28px;
  color: var(--navy);
  margin: 32px 0 8px;
}

.page-lead {
  color: var(--muted);
  margin: 0 0 32px;
  font-size: 15px;
}

.article-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 16px;
  transition: box-shadow 0.15s;
}

.article-card:hover { box-shadow: 0 4px 16px rgba(26, 39, 68, 0.08); }

.article-card h2 {
  font-size: 18px;
  margin: 8px 0 8px;
  line-height: 1.4;
}

.article-card h2 a { color: var(--navy); text-decoration: none; }
.article-card h2 a:hover { color: var(--accent); }

.article-card .desc {
  font-size: 14px;
  color: var(--muted);
  margin: 0;
  line-height: 1.7;
}

/* footer */
footer {
  border-top: 1px solid var(--line);
  padding: 32px 0;
  text-align: center;
  font-size: 13px;
  color: var(--muted);
  margin-top: 48px;
}

footer a { color: var(--muted); }

@media (max-width: 600px) {
  .article-header h1 { font-size: 22px; }
  .article-body { padding: 20px 16px; }
  .nav-links { display: none; }
}