:root {
  --primary-600: #0d9488;
  --primary-500: #14b8a6;
  --primary-50: #f0fdfa;
  --radius-lg: 0.75rem;
  --text-base: 1.125rem;

  --bg: #fafafa;
  --surface: #ffffff;
  --text-primary: #1a1a2e;
  --text-secondary: #555570;
  --text-muted: #8888a0;
  --border: #e4e4ec;
  --accent-container: #2563eb;
  --accent-infra: #0891b2;
  --accent-db: #4f46e5;
  --accent-network: #059669;
  --accent-security: #dc2626;
  --accent-arch: #7c3aed;
  --accent-perf: #d97706;
  --accent-obs: #db2777;
  --accent-lang: #65a30d;
  --accent-frontend: #e11d48;
  --accent-ai: #c026d3;
  --accent-dev: #475569;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP", sans-serif;
  background: var(--bg);
  color: var(--text-primary);
  font-size: var(--text-base);
  line-height: 1.9;
  padding: 2rem 1rem;
}

.container {
  max-width: 720px;
  margin: 0 auto;
}

header {
  text-align: center;
  margin-bottom: 2.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border);
}

header h1 {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

header h1 a {
  color: var(--text-primary);
  text-decoration: none;
}

header .date {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-top: 0.25rem;
}

header .tagline {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-top: 0.5rem;
}

/* ---- article ---- */

.article {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 2rem 1.75rem;
}

.meta-bar {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.article-title {
  font-size: 1.45rem;
  font-weight: 700;
  line-height: 1.5;
  letter-spacing: -0.01em;
  margin-bottom: 0.75rem;
}

.lead {
  color: var(--text-secondary);
  font-size: 0.98rem;
  margin-bottom: 1.5rem;
}

.body-section {
  margin: 1.75rem 0;
}

.body-section h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 0.6rem;
  padding-left: 0.75rem;
  border-left: 4px solid var(--primary-500);
  line-height: 1.5;
}

.body-section p {
  font-size: 0.95rem;
  color: var(--text-secondary);
  margin-bottom: 0.75rem;
}

.body-section strong,
.article p strong {
  color: var(--text-primary);
}

.article code {
  font-family: ui-monospace, "SF Mono", SFMono-Regular, Menlo, monospace;
  font-size: 0.85em;
  background: var(--primary-50);
  color: var(--primary-600);
  padding: 0.1em 0.4em;
  border-radius: 0.3em;
}

pre.diagram,
pre.code {
  font-family: ui-monospace, "SF Mono", SFMono-Regular, Menlo, monospace;
  font-size: 0.78rem;
  line-height: 1.6;
  background: #1a1a2e;
  color: #e4e4ec;
  border-radius: 0.5rem;
  padding: 1rem 1.25rem;
  margin: 0.75rem 0;
  overflow-x: auto;
}

pre.diagram {
  background: var(--primary-50);
  color: var(--text-primary);
  border: 1px dashed var(--primary-500);
}

/* ---- boxes ---- */

.box-title {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}

.tldr,
.analogy,
.practical,
.hands-on,
.misconceptions,
.glossary,
.further-reading {
  border-radius: 0.6rem;
  padding: 0.9rem 1.1rem;
  margin: 1.5rem 0;
  font-size: 0.9rem;
  line-height: 1.75;
  color: var(--text-secondary);
}

.tldr {
  background: var(--primary-50);
  border-left: 4px solid var(--primary-500);
}

.tldr ul,
.misconceptions ul,
.further-reading ul {
  list-style: none;
  padding: 0;
}

.tldr li,
.misconceptions li,
.further-reading li {
  position: relative;
  padding-left: 1.1rem;
  margin-bottom: 0.3rem;
}

.tldr li::before,
.further-reading li::before {
  content: "•";
  position: absolute;
  left: 0;
  color: var(--primary-500);
  font-weight: 700;
}

.analogy {
  background: #fffbeb;
  border-left: 4px solid var(--accent-perf);
}

.practical {
  background: #f0f5ff;
  border-left: 4px solid var(--accent-container);
}

.hands-on {
  background: var(--surface);
  border: 1px solid var(--border);
}

.hands-on pre.code {
  margin: 0.6rem 0;
}

.misconceptions {
  background: #fef2f2;
  border-left: 4px solid var(--accent-security);
}

.misconceptions li::before {
  content: "✗";
  position: absolute;
  left: 0;
  color: var(--accent-security);
  font-weight: 700;
}

.misconceptions .wrong {
  text-decoration: line-through;
  text-decoration-color: var(--accent-security);
}

.glossary {
  background: var(--bg);
  border: 1px solid var(--border);
}

.glossary dt {
  font-weight: 700;
  color: var(--text-primary);
  margin-top: 0.5rem;
}

.glossary dt:first-of-type {
  margin-top: 0;
}

.glossary dd {
  margin-left: 0;
  padding-left: 1rem;
}

.further-reading {
  background: var(--bg);
  border: 1px solid var(--border);
}

.further-reading a {
  color: var(--primary-600);
  font-weight: 600;
  text-decoration: none;
}

.further-reading a:hover {
  text-decoration: underline;
}

/* ---- tags ---- */

.tag {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 600;
  padding: 0.15rem 0.5rem;
  border-radius: 9999px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  flex-shrink: 0;
  /* 未定義カテゴリのフォールバック（tag-* が後勝ちで上書きする） */
  background: #f1f5f9;
  color: #475569;
}

.tag-container { background: var(--primary-50); color: var(--accent-container); }
.tag-infra { background: #ecfeff; color: var(--accent-infra); }
.tag-db { background: #eef2ff; color: var(--accent-db); }
.tag-network { background: #ecfdf5; color: var(--accent-network); }
.tag-security { background: #fef2f2; color: var(--accent-security); }
.tag-arch { background: #f3e8ff; color: var(--accent-arch); }
.tag-perf { background: #fffbeb; color: var(--accent-perf); }
.tag-obs { background: #fdf2f8; color: var(--accent-obs); }
.tag-lang { background: #f7fee7; color: var(--accent-lang); }
.tag-frontend { background: #fff1f2; color: var(--accent-frontend); }
.tag-ai { background: #fdf4ff; color: var(--accent-ai); }
.tag-dev { background: #f1f5f9; color: var(--accent-dev); }

/* ---- archive list (archive/index.html) ---- */

.section {
  margin-bottom: 2rem;
}

.section-title {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.section-title::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--border);
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  margin-bottom: 0.75rem;
  transition: box-shadow 0.15s ease;
}

.card:hover {
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
}

.card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  line-height: 1.5;
}

.card h3 a {
  color: var(--text-primary);
  text-decoration: none;
}

.card h3 a:hover {
  color: var(--primary-500);
}

.card .summary {
  color: var(--text-secondary);
  font-size: 0.92rem;
  line-height: 1.7;
}

.card .meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-top: 0.6rem;
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* ---- site nav + archive toolbar ---- */

header.with-nav {
  border-bottom: none;
  padding-bottom: 0;
  margin-bottom: 0.75rem;
}

header.with-nav .site-name a {
  color: var(--text-secondary);
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  text-decoration: none;
}

header.with-nav .site-name a:hover {
  color: var(--primary-600);
}

.page-title {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 1.25rem;
}

.site-nav {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  margin-bottom: 2rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--border);
  font-size: 0.9rem;
}

.site-nav a {
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 600;
}

.site-nav a:hover,
.site-nav a.active {
  color: var(--primary-600);
}

.recent-articles {
  margin-top: 2.5rem;
}

.recent-more {
  text-align: right;
  margin-top: 0.75rem;
  font-size: 0.9rem;
}

.recent-more a {
  color: var(--primary-600);
  text-decoration: none;
}

.recent-more a:hover {
  text-decoration: underline;
}

.toolbar {
  margin-bottom: 1.75rem;
}

.search-wrap {
  position: relative;
  margin-bottom: 0.9rem;
}

.search-wrap .icon {
  position: absolute;
  left: 0.9rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  font-size: 0.9rem;
  pointer-events: none;
}

#search {
  width: 100%;
  font-size: 1rem;
  font-family: inherit;
  padding: 0.65rem 1rem 0.65rem 2.4rem;
  border: 1px solid var(--border);
  border-radius: 0.6rem;
  background: var(--surface);
  color: var(--text-primary);
  outline: none;
  transition: border-color 0.15s ease;
}

#search:focus { border-color: var(--primary-500); }
#search::placeholder { color: var(--text-muted); }

.chip-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem;
  margin-bottom: 0.5rem;
}

.chip-row .row-label {
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-right: 0.2rem;
  min-width: 3.6rem;
}

.chip {
  font-size: 0.8rem;
  font-weight: 600;
  font-family: inherit;
  padding: 0.2rem 0.75rem;
  border-radius: 9999px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.12s ease;
}

.chip:hover {
  border-color: var(--primary-500);
  color: var(--primary-600);
}

.chip.on {
  background: var(--primary-600);
  border-color: var(--primary-600);
  color: #fff;
}

.chip-count { opacity: 0.65; font-weight: 400; }

.result-info {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 0.6rem;
  min-height: 1.2em;
}

.section-title .count {
  font-weight: 400;
  letter-spacing: 0;
  text-transform: none;
}

.term-hit {
  display: none;
  font-size: 0.75rem;
  color: var(--primary-600);
  margin-top: 0.35rem;
}

.term-hit.show { display: block; }

.empty {
  display: none;
  text-align: center;
  color: var(--text-muted);
  padding: 3rem 1rem;
  font-size: 0.95rem;
}

.empty.show { display: block; }

/* ---- footer ---- */

footer {
  text-align: center;
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.8rem;
}

footer a {
  color: var(--primary-600);
  text-decoration: none;
}

.archive-link {
  display: inline-block;
  margin-top: 1rem;
  color: var(--primary-600);
  font-size: 0.9rem;
  text-decoration: none;
}

.archive-link:hover {
  text-decoration: underline;
}

@media (max-width: 600px) {
  body { padding: 1rem 0.75rem; }
  header h1 { font-size: 1.4rem; }
  .article { padding: 1.25rem 1rem; }
  .article-title { font-size: 1.2rem; }
  .lead { font-size: 0.92rem; }
  .body-section p { font-size: 0.9rem; }
  .meta-bar { gap: 0.5rem; }
  pre.diagram, pre.code { font-size: 0.7rem; padding: 0.75rem; }
  .card { padding: 1rem; }
  .chip-row .row-label { min-width: 100%; margin-bottom: -0.1rem; }
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f0f1a;
    --surface: #1a1a2e;
    --text-primary: #e4e4ec;
    --text-secondary: #a0a0b8;
    --text-muted: #6b6b80;
    --border: #2a2a3e;
    --primary-50: #0e2a28;
    --primary-600: #2dd4bf;
    --primary-500: #2dd4bf;
  }

  .tag-container { background: #0a1a3d; }
  .tag-infra { background: #0a2d3d; }
  .tag-db { background: #1a1a4d; }
  .tag-network { background: #0a3d2a; }
  .tag-security { background: #3d0a0a; }
  .tag-arch { background: #2d1b69; }
  .tag-perf { background: #3d2a0a; }
  .tag-obs { background: #3d0a2d; }
  .tag-lang { background: #1f3d0a; }
  .tag-frontend { background: #3d0a14; }
  .tag-ai { background: #380a3d; }
  .tag-dev { background: #1e293b; color: #94a3b8; }

  .analogy { background: #2a2510; }
  .practical { background: #141a2e; }
  .misconceptions { background: #2a1010; }
  pre.diagram { background: #0e2a28; color: #e4e4ec; }
  .article code { color: #2dd4bf; }
}