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

:root {
  --bg: #0f1117;
  --surface: #1a1d27;
  --border: #2a2d3a;
  --accent: #7c6af7;
  --accent-light: #a89cf8;
  --text: #e2e4ed;
  --muted: #8b8fa8;
  --tag-bg: #252838;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Hiragino Sans', 'Hiragino Kaku Gothic ProN', 'Noto Sans JP', sans-serif;
  font-size: 16px;
  line-height: 1.8;
  min-height: 100vh;
}

a { color: var(--accent-light); text-decoration: none; }
a:hover { color: #fff; }

/* ===== Header ===== */
header {
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
}
.header-inner {
  max-width: 800px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}
.site-title {
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: .05em;
  color: var(--text);
}
.site-title span { color: var(--accent); }

/* ===== Main ===== */
main {
  max-width: 800px;
  margin: 0 auto;
  padding: 48px 24px 80px;
}

/* ===== Hero (index only) ===== */
.hero {
  padding: 48px 0 56px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 48px;
}
.hero h1 {
  font-size: clamp(1.6rem, 4vw, 2.2rem);
  font-weight: 800;
  line-height: 1.3;
  margin-bottom: 12px;
}
.hero p { color: var(--muted); font-size: .95rem; }

/* ===== Article cards ===== */
.articles { display: flex; flex-direction: column; gap: 1px; }

.card {
  display: block;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 28px 32px;
  margin-bottom: 16px;
  transition: border-color .2s, transform .2s;
}
.card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
  color: var(--text);
}
.card-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 12px;
  font-size: .8rem;
  color: var(--muted);
}
.tag {
  background: var(--tag-bg);
  color: var(--accent-light);
  padding: 2px 10px;
  border-radius: 20px;
  font-size: .75rem;
}
.card h2 {
  font-size: 1.15rem;
  font-weight: 700;
  line-height: 1.5;
  margin-bottom: 10px;
  color: var(--text);
}
.card p { font-size: .9rem; color: var(--muted); line-height: 1.7; }

/* ===== Article page ===== */
.article-header {
  padding: 40px 0 36px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 48px;
}
.article-header .meta {
  display: flex;
  gap: 12px;
  align-items: center;
  margin-bottom: 20px;
  font-size: .8rem;
  color: var(--muted);
}
.article-header h1 {
  font-size: clamp(1.4rem, 4vw, 1.9rem);
  font-weight: 800;
  line-height: 1.4;
}

.article-body { max-width: 680px; }
.article-body h2 {
  font-size: 1.2rem;
  font-weight: 700;
  margin: 48px 0 16px;
  padding-left: 14px;
  border-left: 3px solid var(--accent);
}
.article-body h3 {
  font-size: 1rem;
  font-weight: 700;
  margin: 32px 0 12px;
  color: var(--accent-light);
}
.article-body p { margin-bottom: 20px; color: var(--text); }
.article-body ul, .article-body ol {
  margin: 0 0 20px 24px;
  color: var(--text);
}
.article-body li { margin-bottom: 8px; }
.article-body strong { color: #fff; font-weight: 700; }
.article-body table {
  width: 100%;
  border-collapse: collapse;
  margin: 24px 0;
  font-size: .9rem;
}
.article-body th {
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 10px 14px;
  text-align: left;
  color: var(--muted);
  font-weight: 600;
}
.article-body td {
  border: 1px solid var(--border);
  padding: 10px 14px;
}
.article-body blockquote {
  border-left: 3px solid var(--accent);
  padding: 12px 20px;
  margin: 24px 0;
  background: var(--surface);
  border-radius: 0 8px 8px 0;
  color: var(--muted);
}

/* ===== Back link ===== */
.back { margin-bottom: 32px; font-size: .9rem; color: var(--muted); }
.back a { color: var(--accent-light); }
.back a:hover { color: #fff; }

/* ===== Footer ===== */
footer {
  border-top: 1px solid var(--border);
  padding: 24px;
  text-align: center;
  font-size: .8rem;
  color: var(--muted);
}

@media (max-width: 600px) {
  .card { padding: 20px; }
  .article-header h1 { font-size: 1.3rem; }
}