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

:root {
  --font: 'Inter', 'Noto Sans JP', -apple-system, sans-serif;
  --ease: cubic-bezier(0.16, 1, 0.3, 1);
  --accent: #c97b5b;
  --accent-light: #e09070;
  --max-w: 780px;
  --max-w-wide: 1080px;
  --pad: 40px;
}

[data-theme="dark"] {
  --bg: #060606;
  --bg-card: #0f0f0f;
  --bg-card-hover: #161616;
  --bg-nav: rgba(6,6,6,0.92);
  --border: #181818;
  --border-hover: #2a2a2a;
  --text: #eee;
  --text-sub: #9a9a9a;
  --text-muted: #6a6a6a;
  --accent-glow: rgba(201,123,91,0.10);
  --cta-text: #060606;
}

[data-theme="light"] {
  --bg: #f5f3f0;
  --bg-card: #fff;
  --bg-card-hover: #faf8f5;
  --bg-nav: rgba(245,243,240,0.94);
  --border: #e0dbd4;
  --border-hover: #ccc;
  --text: #1a1a1a;
  --text-sub: #666;
  --text-muted: #aaa;
  --accent-glow: rgba(201,123,91,0.07);
  --cta-text: #fff;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.9;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
  transition: background 0.5s var(--ease), color 0.5s var(--ease);
}

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

.reveal {
  opacity: 0; transform: translateY(24px);
  transition: opacity 0.7s var(--ease), transform 0.7s var(--ease);
}
.reveal.visible { opacity: 1; transform: translateY(0); }
.rv1 { transition-delay: 0.1s; }
.rv2 { transition-delay: 0.2s; }
.rv3 { transition-delay: 0.3s; }

/* NAV */
nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  background: var(--bg-nav);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
  transition: background 0.5s var(--ease), border-color 0.5s var(--ease);
}

.nav-inner {
  max-width: var(--max-w-wide); margin: 0 auto;
  padding: 0 var(--pad); height: 56px;
  display: flex; align-items: center; justify-content: space-between;
}

.nav-back {
  font-size: 0.72rem; font-weight: 500;
  color: var(--text-sub); letter-spacing: 0.05em;
  display: flex; align-items: center; gap: 8px;
  transition: color 0.2s;
}

.nav-back:hover { color: var(--text); }

.nav-back svg {
  width: 14px; height: 14px; stroke: currentColor; fill: none;
  stroke-width: 2; stroke-linecap: round; stroke-linejoin: round;
}

.theme-toggle {
  width: 32px; height: 32px; border-radius: 6px;
  border: 1px solid var(--border); background: transparent;
  cursor: pointer; display: flex; align-items: center; justify-content: center;
  transition: all 0.3s; color: var(--text-muted);
}

.theme-toggle:hover { border-color: var(--accent); color: var(--accent); }

.theme-toggle svg {
  width: 14px; height: 14px; stroke: currentColor; fill: none;
  stroke-width: 2; stroke-linecap: round; stroke-linejoin: round;
}

.theme-toggle .icon-sun { display: none; }
.theme-toggle .icon-moon { display: block; }
[data-theme="light"] .theme-toggle .icon-sun { display: block; }
[data-theme="light"] .theme-toggle .icon-moon { display: none; }

/* ARTICLE LIST PAGE */
.list-hero {
  max-width: var(--max-w-wide); margin: 0 auto;
  padding: 120px var(--pad) 60px;
}

.list-label {
  font-size: 0.6rem; font-weight: 600;
  letter-spacing: 0.35em; text-transform: uppercase;
  color: var(--accent); margin-bottom: 20px;
  display: flex; align-items: center; gap: 12px;
}

.list-label::before {
  content: ''; width: 20px; height: 1px; background: var(--accent);
}

.list-title {
  font-size: clamp(1.6rem, 4vw, 2.4rem);
  font-weight: 800; letter-spacing: -0.02em;
  line-height: 1.4; margin-bottom: 12px;
}

.list-title .accent { color: var(--accent); }

.list-desc {
  font-size: 0.9rem; color: var(--text-sub);
  line-height: 2; max-width: 600px;
  transition: color 0.5s var(--ease);
}

/* Article cards grid */
.articles-grid {
  max-width: var(--max-w-wide); margin: 0 auto;
  padding: 0 var(--pad) 80px;
  display: flex; flex-direction: column;
}

.article-card {
  display: grid; grid-template-columns: 80px 1fr;
  align-items: center; gap: 24px;
  padding: 28px 0;
  border-bottom: 1px solid var(--border);
  transition: all 0.3s var(--ease);
  color: inherit;
}

.article-card:first-child {
  border-top: 1px solid var(--border);
}

.article-card:hover { padding-left: 12px; }

.article-card-num {
  font-size: 2.4rem; font-weight: 900;
  color: var(--accent);
  font-variant-numeric: tabular-nums;
}

.article-card-title {
  font-size: 1.05rem; font-weight: 600;
  transition: color 0.3s;
}

.article-card:hover .article-card-title { color: var(--accent); }

.article-card-desc {
  font-size: 0.75rem; color: var(--text-muted);
  margin-top: 4px;
  transition: color 0.5s var(--ease);
}

.article-card-arrow { display: none; }

/* ARTICLE DETAIL PAGE */
.article {
  max-width: var(--max-w); margin: 0 auto;
  padding: 100px var(--pad) 80px;
}

.article-hero {
  margin-bottom: 56px;
  padding-bottom: 40px;
  border-bottom: 1px solid var(--border);
  transition: border-color 0.5s var(--ease);
}

.article-num {
  font-size: 0.6rem; font-weight: 700;
  letter-spacing: 0.35em; color: var(--accent);
  margin-bottom: 16px;
}

.article-title {
  font-size: clamp(1.4rem, 3.5vw, 2rem);
  font-weight: 800; letter-spacing: -0.02em;
  line-height: 1.4; margin-bottom: 16px;
}

.article-meta {
  font-size: 0.7rem; color: var(--text-muted);
  transition: color 0.5s var(--ease);
}

.article-body p {
  font-size: 0.92rem; color: var(--text-sub);
  line-height: 2.3; margin-bottom: 20px;
  transition: color 0.5s var(--ease);
}

.article-body p strong {
  color: var(--text); font-weight: 600;
  transition: color 0.5s var(--ease);
}

.callout {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: 0 8px 8px 0;
  padding: 24px 28px;
  margin: 28px 0;
  transition: all 0.5s var(--ease);
}

.callout p { font-size: 0.85rem; margin-bottom: 0; }

/* Tool grid */
.tool-grid {
  display: grid; grid-template-columns: 1fr 1fr;
  gap: 12px; margin: 24px 0;
}

.tool-item {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: 8px; padding: 16px 20px;
  transition: all 0.3s var(--ease);
}

.tool-item:hover { border-color: var(--accent); transform: translateY(-2px); }

.tool-item-label {
  font-size: 0.6rem; font-weight: 600;
  letter-spacing: 0.15em; color: var(--accent); margin-bottom: 4px;
}

.tool-item-name { font-size: 0.85rem; font-weight: 600; }

.tool-item-desc {
  font-size: 0.72rem; color: var(--text-muted); margin-top: 2px;
  transition: color 0.5s var(--ease);
}

/* Navigation between articles */
.article-nav {
  display: flex; justify-content: space-between; align-items: center;
  margin-top: 64px; padding-top: 32px;
  border-top: 1px solid var(--border);
  transition: border-color 0.5s var(--ease);
}

.article-nav a {
  font-size: 0.78rem; font-weight: 500;
  color: var(--text-sub); display: flex; align-items: center; gap: 8px;
  transition: color 0.2s;
}

.article-nav a:hover { color: var(--accent); }

.article-nav svg {
  width: 14px; height: 14px; stroke: currentColor; fill: none;
  stroke-width: 2; stroke-linecap: round; stroke-linejoin: round;
}

/* CTA */
.cta-section {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: 12px; padding: 48px 40px;
  text-align: center; margin-top: 56px;
  position: relative; overflow: hidden;
  transition: all 0.5s var(--ease);
}

.cta-section::before {
  content: ''; position: absolute;
  top: 0; left: 0; right: 0; height: 2px;
  background: linear-gradient(90deg, var(--accent), transparent 80%);
}

.cta-section p {
  font-size: 0.85rem; color: var(--text-sub); margin-bottom: 24px; text-align: center;
  transition: color 0.5s var(--ease);
}

.cta-button {
  display: inline-flex; align-items: center; gap: 10px;
  background: var(--accent); color: var(--cta-text);
  font-weight: 600; font-size: 0.85rem; letter-spacing: 0.05em;
  padding: 14px 32px; border-radius: 8px;
  transition: all 0.3s var(--ease);
}

.cta-button:hover {
  background: var(--accent-light); color: var(--cta-text);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(201,123,91,0.25);
}

.cta-button svg {
  width: 16px; height: 16px; stroke: currentColor;
  fill: none; stroke-width: 2; stroke-linecap: round;
}

/* Footer */
.page-footer {
  max-width: var(--max-w-wide); margin: 0 auto;
  padding: 32px var(--pad);
  border-top: 1px solid var(--border);
  display: flex; justify-content: space-between; align-items: center;
  transition: border-color 0.5s var(--ease);
}

.page-footer span {
  font-size: 0.6rem; color: var(--text-muted);
  transition: color 0.5s var(--ease);
}

@media (max-width: 640px) {
  :root { --pad: 20px; }
  .tool-grid { grid-template-columns: 1fr; }
  .article-card { grid-template-columns: 40px 1fr auto; gap: 16px; }
  .article-nav { flex-direction: column; gap: 16px; }
  .page-footer { flex-direction: column; gap: 8px; text-align: center; }
}