/* ======= Reset & Base ======= */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --color-bg: #fafaf9;
  --color-surface: #ffffff;
  --color-text: #1c1917;
  --color-text-muted: #78716c;
  --color-accent: #d97706;    /* amber — warm, "typing hand" feel */
  --color-accent-hover: #b45309;
  --color-border: #e7e5e4;
  --color-card-hover: #f5f5f4;
  --font-sans: 'Segoe UI', system-ui, -apple-system, sans-serif;
  --font-mono: 'SF Mono', 'Cascadia Code', monospace;
  --max-width: 800px;
  --radius: 8px;
}

html {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
}

body {
  min-height: 100vh;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color 0.2s;
}
a:hover {
  color: var(--color-accent-hover);
}

img {
  max-width: 100%;
  height: auto;
}

/* ======= Layout ======= */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ======= Nav ======= */
nav {
  padding: 1.25rem 0;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: 3rem;
}
.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  gap: 2rem;
}
.nav-brand {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.02em;
}
.nav-brand:hover {
  color: var(--color-accent);
}
.nav-links {
  display: flex;
  gap: 1.25rem;
}
.nav-links a {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  font-weight: 500;
}
.nav-links a:hover,
.nav-links a[aria-current] {
  color: var(--color-accent);
}

/* ======= Column Cards (Home Page) ======= */
.column-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0 3rem;
}
.column-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 2rem 1.5rem;
  transition: all 0.2s;
  display: block;
  color: inherit;
  text-align: center;
}
.column-card:hover {
  border-color: var(--color-accent);
  background: var(--color-card-hover);
  transform: translateY(-2px);
}
.column-card .column-icon {
  font-size: 2rem;
  display: block;
  margin-bottom: 1rem;
}
.column-card h2 {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
}
.column-card p {
  color: var(--color-text-muted);
  font-size: 0.925rem;
  line-height: 1.5;
}
.column-card .nav-en {
  font-weight: 400;
  opacity: 0.5;
  font-size: 0.75rem;
}
.home-footer {
  text-align: center;
  padding: 2rem 0;
  margin-top: 2rem;
}
.home-footer a {
  font-weight: 600;
}
@media (max-width: 640px) {
  .column-grid {
    grid-template-columns: 1fr;
  }
}

/* ======= Hero ======= */
.hero {
  text-align: center;
  padding: 4rem 0 3rem;
}
.hero h1 {
  font-size: 2.5rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 1rem;
}
.hero .subtitle {
  font-size: 1.1rem;
  color: var(--color-text-muted);
  max-width: 600px;
  margin: 0 auto 2rem;
  line-height: 1.5;
}
.hero .tagline {
  font-size: 0.85rem;
  color: var(--color-accent);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 0.75rem;
}

/* ======= Cards ======= */
.card-grid {
  display: grid;
  gap: 1.5rem;
  margin: 2rem 0 4rem;
}
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: all 0.2s;
  display: block;
  color: inherit;
}
.card:hover {
  border-color: var(--color-accent);
  background: var(--color-card-hover);
  transform: translateY(-1px);
}
.card-meta {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-bottom: 0.5rem;
  display: flex;
  gap: 0.75rem;
  align-items: center;
}
.card h2 {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  line-height: 1.3;
}
.card p {
  color: var(--color-text-muted);
  font-size: 0.925rem;
  line-height: 1.5;
}
.card-tags {
  display: flex;
  gap: 0.5rem;
  margin-top: 0.75rem;
  flex-wrap: wrap;
}
.tag {
  font-size: 0.75rem;
  padding: 0.15rem 0.6rem;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 99px;
  color: var(--color-text-muted);
}
.card-badge {
  font-size: 0.7rem;
  font-weight: 600;
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  background: #fef3c7;
  color: #92400e;
}

/* ======= Section Headers ======= */
.section-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin: 3rem 0 1rem;
}
.section-header h2 {
  font-size: 1.5rem;
  font-weight: 700;
}
.section-header a {
  font-size: 0.85rem;
  font-weight: 500;
}

/* ======= Content Page ======= */
.content-page {
  max-width: 680px;
  margin: 0 auto;
  padding: 0 1.5rem 4rem;
}
.content-page h1 {
  font-size: 2rem;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 0.5rem;
}
.content-page .meta {
  color: var(--color-text-muted);
  font-size: 0.9rem;
  margin-bottom: 2rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--color-border);
}
.content-page h2 {
  font-size: 1.35rem;
  font-weight: 700;
  margin: 2rem 0 0.75rem;
}
.content-page h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin: 1.5rem 0 0.5rem;
}
.content-page p {
  margin-bottom: 1rem;
}
.content-page ul, .content-page ol {
  margin-bottom: 1rem;
  padding-left: 1.5rem;
}
.content-page li {
  margin-bottom: 0.25rem;
}
.content-page table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  font-size: 0.9rem;
}
.content-page th, .content-page td {
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--color-border);
  text-align: left;
}
.content-page th {
  background: var(--color-bg);
  font-weight: 600;
}
.content-page .cta-box {
  margin-top: 3rem;
  padding: 1.5rem;
  background: #fffbeb;
  border: 1px solid #fde68a;
  border-radius: var(--radius);
  text-align: center;
}
.content-page .cta-box a {
  display: inline-block;
  background: var(--color-accent);
  color: white;
  font-weight: 600;
  padding: 0.6rem 1.5rem;
  border-radius: var(--radius);
  margin-top: 0.75rem;
}
.content-page .cta-box a:hover {
  background: var(--color-accent-hover);
}

/* ======= Footer ======= */
footer {
  text-align: center;
  padding: 2rem 0;
  color: var(--color-text-muted);
  font-size: 0.8rem;
  border-top: 1px solid var(--color-border);
  margin-top: 4rem;
}

/* ======= Page Header ======= */
.page-header {
  margin-bottom: 2.5rem;
}
.page-header h1 {
  font-size: 2rem;
  font-weight: 800;
}
.page-header p {
  color: var(--color-text-muted);
  margin-top: 0.5rem;
}