/* ===== CSS Variables ===== */
:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-primary-light: #dbeafe;
  --color-secondary: #059669;
  --color-secondary-light: #d1fae5;
  --color-text: #1f2937;
  --color-text-light: #6b7280;
  --color-text-lighter: #9ca3af;
  --color-bg: #ffffff;
  --color-bg-alt: #f9fafb;
  --color-bg-card: #ffffff;
  --color-border: #e5e7eb;
  --color-border-light: #f3f4f6;
  --color-accent: #f59e0b;
  --color-error: #dc2626;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.07), 0 2px 4px -1px rgba(0,0,0,0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -2px rgba(0,0,0,0.04);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --font-sans: 'Pretendard', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --max-width: 1200px;
  --content-width: 800px;
  --header-height: 64px;
  --transition: 0.2s ease;
}

/* ===== Reset & Base ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--color-primary); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--color-primary-dark); }
ul, ol { list-style: none; }
button { cursor: pointer; border: none; background: none; font-family: inherit; }
input, textarea, select { font-family: inherit; font-size: inherit; }

/* ===== Container ===== */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 24px; }

/* ===== Header ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  height: var(--header-height);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
}
.site-logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.02em;
}
.site-logo:hover { color: var(--color-primary); }
.nav-toggle { display: none; font-size: 1.5rem; padding: 8px; color: var(--color-text); }
.nav-list { display: flex; gap: 8px; }
.nav-list li a {
  display: block;
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  color: var(--color-text-light);
  font-size: 0.9rem;
  font-weight: 500;
  transition: all var(--transition);
}
.nav-list li a:hover,
.nav-list li a.active {
  color: var(--color-primary);
  background: var(--color-primary-light);
}

/* ===== Buttons ===== */
.btn {
  display: inline-block;
  padding: 10px 20px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 600;
  text-align: center;
  transition: all var(--transition);
  line-height: 1.4;
}
.btn-primary { background: var(--color-primary); color: #fff; }
.btn-primary:hover { background: var(--color-primary-dark); color: #fff; }
.btn-outline { border: 1px solid var(--color-border); color: var(--color-text); background: var(--color-bg); }
.btn-outline:hover { border-color: var(--color-primary); color: var(--color-primary); }
.btn-small { padding: 6px 12px; font-size: 0.8rem; }
.btn-full { width: 100%; }
.btn-group { display: flex; gap: 8px; flex-wrap: wrap; }

/* ===== Hero ===== */
.hero {
  padding: 80px 0 60px;
  background: linear-gradient(135deg, var(--color-primary-light) 0%, var(--color-bg) 100%);
  border-bottom: 1px solid var(--color-border-light);
}
.hero h1 {
  font-size: 2rem;
  font-weight: 800;
  line-height: 1.3;
  color: var(--color-text);
  margin-bottom: 16px;
  letter-spacing: -0.02em;
}
.hero-subtitle {
  font-size: 1.1rem;
  color: var(--color-text-light);
  margin-bottom: 12px;
  max-width: 640px;
}
.hero-desc {
  font-size: 0.95rem;
  color: var(--color-text-lighter);
  margin-bottom: 28px;
  max-width: 640px;
}

/* ===== Sections ===== */
.section { padding: 60px 0; }
.section:nth-child(even) { background: var(--color-bg-alt); }
.section-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--color-text);
}
.section-desc {
  color: var(--color-text-light);
  margin-bottom: 32px;
  font-size: 0.95rem;
}
.section-more { margin-top: 32px; text-align: center; }

/* ===== Category Grid ===== */
.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
}
.category-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 24px;
  transition: all var(--transition);
}
.category-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}
.category-card-icon { font-size: 1.5rem; margin-bottom: 12px; }
.category-card h3 { font-size: 1.1rem; font-weight: 600; margin-bottom: 8px; }
.category-card h3 a { color: var(--color-text); }
.category-card h3 a:hover { color: var(--color-primary); }
.category-card p { font-size: 0.88rem; color: var(--color-text-light); line-height: 1.6; }
.category-card .post-count { font-size: 0.8rem; color: var(--color-text-lighter); margin-top: 12px; }

.category-detail-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 24px;
}

/* ===== Post Grid & List ===== */
.post-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 20px;
}
.post-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 24px;
  transition: all var(--transition);
}
.post-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-md);
}
.post-card-category {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-primary);
  background: var(--color-primary-light);
  padding: 3px 8px;
  border-radius: 4px;
  margin-bottom: 10px;
}
.post-card h3 { font-size: 1.05rem; font-weight: 600; margin-bottom: 8px; line-height: 1.4; }
.post-card h3 a { color: var(--color-text); }
.post-card h3 a:hover { color: var(--color-primary); }
.post-card p { font-size: 0.88rem; color: var(--color-text-light); line-height: 1.6; }
.post-card-meta {
  margin-top: 14px;
  font-size: 0.8rem;
  color: var(--color-text-lighter);
}

.post-list .post-card { margin-bottom: 16px; }

/* ===== Filter Bar ===== */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 28px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--color-border-light);
}
.filter-btn {
  padding: 6px 14px;
  border-radius: 20px;
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--color-text-light);
  border: 1px solid var(--color-border);
  background: var(--color-bg);
  transition: all var(--transition);
}
.filter-btn:hover,
.filter-btn.active {
  color: var(--color-primary);
  border-color: var(--color-primary);
  background: var(--color-primary-light);
}

/* ===== Column List ===== */
.column-list, .column-list-full { display: flex; flex-direction: column; gap: 16px; }
.column-item {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 24px;
  transition: all var(--transition);
}
.column-item:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-sm);
}
.column-item h3 { font-size: 1.05rem; font-weight: 600; margin-bottom: 6px; }
.column-item h3 a { color: var(--color-text); }
.column-item h3 a:hover { color: var(--color-primary); }
.column-item .column-subtitle { font-size: 0.88rem; color: var(--color-text-light); margin-bottom: 8px; }
.column-item .column-meta { font-size: 0.8rem; color: var(--color-text-lighter); }

/* ===== Purpose & CTA Boxes ===== */
.purpose-box, .cta-box {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 40px;
}
.purpose-box h2, .cta-box h2 { font-size: 1.3rem; font-weight: 700; margin-bottom: 12px; }
.purpose-box p, .cta-box p { color: var(--color-text-light); margin-bottom: 12px; font-size: 0.95rem; }
.cta-box { text-align: center; background: linear-gradient(135deg, var(--color-primary-light), var(--color-bg)); }

/* ===== Principles ===== */
.principles-list { display: flex; flex-direction: column; gap: 12px; }
.principles-list li {
  padding: 14px 20px;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 0.92rem;
  color: var(--color-text);
  position: relative;
  padding-left: 36px;
}
.principles-list li::before {
  content: '✓';
  position: absolute;
  left: 14px;
  color: var(--color-secondary);
  font-weight: 700;
}

/* ===== Author Mini Box ===== */
.author-mini-box {
  display: flex;
  align-items: center;
  gap: 20px;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 24px;
}
.author-mini-icon { font-size: 2rem; }
.author-mini-content h3 { font-size: 1rem; font-weight: 600; margin-bottom: 4px; }
.author-mini-content p { font-size: 0.9rem; color: var(--color-text-light); margin-bottom: 10px; }
.author-link { color: var(--color-primary); font-weight: 600; }

/* ===== Author Profile ===== */
.author-profile-box {
  display: flex;
  align-items: center;
  gap: 20px;
  padding: 24px;
  background: var(--color-bg-alt);
  border-radius: var(--radius-md);
  margin-bottom: 32px;
}
.author-profile-icon { font-size: 3rem; }
.author-profile-info h2 { margin-bottom: 4px; }
.author-profile-info p { color: var(--color-text-light); font-size: 0.95rem; }

/* ===== Breadcrumb ===== */
.breadcrumb {
  padding: 16px 0;
  font-size: 0.82rem;
  color: var(--color-text-lighter);
}
.breadcrumb a { color: var(--color-text-light); }
.breadcrumb a:hover { color: var(--color-primary); }

/* ===== Page Title ===== */
.page-title {
  font-size: 1.75rem;
  font-weight: 800;
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}
.page-desc {
  color: var(--color-text-light);
  margin-bottom: 32px;
  font-size: 0.95rem;
  max-width: 640px;
}

/* ===== Content Body ===== */
.content-page { padding-bottom: 60px; }
.content-body { max-width: var(--content-width); }
.content-body h2 {
  font-size: 1.3rem;
  font-weight: 700;
  margin-top: 40px;
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--color-border-light);
}
.content-body h3 { font-size: 1.1rem; font-weight: 600; margin-top: 28px; margin-bottom: 8px; }
.content-body p { margin-bottom: 16px; font-size: 0.95rem; line-height: 1.8; }
.content-body ul, .content-body ol { margin-bottom: 16px; padding-left: 24px; }
.content-body ul { list-style: disc; }
.content-body ol { list-style: decimal; }
.content-body li { margin-bottom: 6px; font-size: 0.93rem; line-height: 1.7; }
.content-body strong { font-weight: 600; }
.content-body a { color: var(--color-primary); text-decoration: underline; text-underline-offset: 2px; }

/* ===== Post Detail ===== */
.post-detail-header { margin-bottom: 32px; }
.post-detail-header .post-category-badge {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-primary);
  background: var(--color-primary-light);
  padding: 4px 10px;
  border-radius: 4px;
  margin-bottom: 12px;
}
.post-detail-header h1 { font-size: 1.75rem; font-weight: 800; margin-bottom: 8px; line-height: 1.3; }
.post-detail-header .post-subtitle { font-size: 1rem; color: var(--color-text-light); margin-bottom: 16px; }
.post-detail-meta { font-size: 0.82rem; color: var(--color-text-lighter); display: flex; gap: 16px; flex-wrap: wrap; }

.post-toc {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  margin-bottom: 32px;
}
.post-toc h4 { font-size: 0.9rem; font-weight: 600; margin-bottom: 10px; color: var(--color-text); }
.post-toc ol { list-style: decimal; padding-left: 20px; }
.post-toc li { font-size: 0.88rem; margin-bottom: 4px; color: var(--color-text-light); }

.post-key-points {
  background: var(--color-secondary-light);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  margin: 32px 0;
}
.post-key-points h4 { font-size: 0.9rem; font-weight: 600; margin-bottom: 8px; color: var(--color-secondary); }
.post-key-points p { font-size: 0.9rem; color: var(--color-text); margin: 0; }

.post-faq { margin-top: 40px; }
.post-faq h3 { font-size: 1.1rem; font-weight: 600; margin-bottom: 16px; }
.faq-item { margin-bottom: 16px; padding: 16px; background: var(--color-bg-alt); border-radius: var(--radius-sm); }
.faq-item .faq-q { font-weight: 600; font-size: 0.92rem; margin-bottom: 6px; color: var(--color-text); }
.faq-item .faq-a { font-size: 0.88rem; color: var(--color-text-light); line-height: 1.6; }

.post-related { margin-top: 40px; padding-top: 24px; border-top: 1px solid var(--color-border); }
.post-related h3 { font-size: 1.1rem; font-weight: 600; margin-bottom: 16px; }
.related-list { display: flex; flex-direction: column; gap: 8px; }
.related-list a { font-size: 0.9rem; padding: 10px 14px; background: var(--color-bg-alt); border-radius: var(--radius-sm); color: var(--color-text); }
.related-list a:hover { background: var(--color-primary-light); color: var(--color-primary); }

/* ===== Legal Content ===== */
.legal-content h2 { font-size: 1.1rem; }
.legal-date { margin-top: 32px; font-size: 0.85rem; color: var(--color-text-lighter); }

/* ===== Contact Form ===== */
.contact-email { font-size: 1.2rem; font-weight: 600; }
.contact-email a { color: var(--color-primary); }
.contact-form { margin: 24px 0; }
.form-group { margin-bottom: 16px; }
.form-group label { display: block; font-size: 0.88rem; font-weight: 600; margin-bottom: 6px; color: var(--color-text); }
.form-group input, .form-group textarea {
  width: 100%;
  padding: 10px 14px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  transition: border-color var(--transition);
}
.form-group input:focus, .form-group textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-light);
}

/* ===== Notice Box ===== */
.notice-box {
  background: #fef3c7;
  border: 1px solid #fbbf24;
  border-radius: var(--radius-sm);
  padding: 14px 18px;
  font-size: 0.88rem;
  color: #92400e;
  margin-bottom: 20px;
  line-height: 1.6;
}

/* ===== Sitemap ===== */
.sitemap-list { list-style: none; padding: 0; }
.sitemap-list li { margin-bottom: 8px; }
.sitemap-list li a { font-size: 0.92rem; }

/* ===== Error Page ===== */
.error-page { text-align: center; padding: 80px 0; }
.error-content h1 { font-size: 5rem; font-weight: 800; color: var(--color-primary); margin-bottom: 8px; }
.error-content h2 { font-size: 1.3rem; margin-bottom: 12px; }
.error-content p { color: var(--color-text-light); margin-bottom: 24px; }
.error-actions { display: flex; gap: 12px; justify-content: center; }

/* ===== Footer ===== */
.site-footer {
  margin-top: auto;
  background: var(--color-bg-alt);
  border-top: 1px solid var(--color-border);
  padding: 48px 0 24px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 32px;
  margin-bottom: 32px;
}
.footer-about h3 { font-size: 1.1rem; font-weight: 700; margin-bottom: 8px; }
.footer-about p { font-size: 0.85rem; color: var(--color-text-light); }
.footer-links h4, .footer-contact h4 { font-size: 0.9rem; font-weight: 600; margin-bottom: 12px; }
.footer-links ul li { margin-bottom: 6px; }
.footer-links ul li a { font-size: 0.85rem; color: var(--color-text-light); }
.footer-links ul li a:hover { color: var(--color-primary); }
.footer-contact p { font-size: 0.85rem; color: var(--color-text-light); margin-bottom: 4px; }
.footer-bottom { padding-top: 20px; border-top: 1px solid var(--color-border); text-align: center; }
.footer-bottom p { font-size: 0.8rem; color: var(--color-text-lighter); }

/* ===== Admin Styles ===== */
.admin-body { background: var(--color-bg-alt); }
.admin-login {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}
.admin-login-box {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 40px;
  max-width: 420px;
  width: 100%;
  box-shadow: var(--shadow-lg);
}
.admin-login-box h1 { font-size: 1.4rem; font-weight: 700; margin-bottom: 4px; }
.admin-subtitle { font-size: 0.88rem; color: var(--color-text-light); margin-bottom: 20px; }

.admin-dashboard { display: flex; min-height: 100vh; }
.admin-sidebar {
  width: 240px;
  background: var(--color-bg);
  border-right: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 50;
}
.admin-sidebar-header { padding: 20px; border-bottom: 1px solid var(--color-border); }
.admin-logo { font-size: 1rem; font-weight: 700; color: var(--color-text); }
.admin-badge {
  display: inline-block;
  font-size: 0.7rem;
  background: var(--color-primary-light);
  color: var(--color-primary);
  padding: 2px 6px;
  border-radius: 4px;
  margin-left: 6px;
  font-weight: 600;
}
.admin-nav { flex: 1; padding: 16px 12px; }
.admin-nav ul { display: flex; flex-direction: column; gap: 4px; }
.admin-nav-item {
  display: block;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.88rem;
  color: var(--color-text-light);
  transition: all var(--transition);
}
.admin-nav-item:hover, .admin-nav-item.active {
  background: var(--color-primary-light);
  color: var(--color-primary);
}
.admin-sidebar-footer { padding: 16px; border-top: 1px solid var(--color-border); display: flex; gap: 8px; flex-wrap: wrap; }

.admin-main { flex: 1; margin-left: 240px; padding: 32px; }
.admin-section h2 { font-size: 1.4rem; font-weight: 700; margin-bottom: 24px; }
.admin-section-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 24px; }
.admin-section-header h2 { margin-bottom: 0; }

.admin-stats {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 16px;
  margin-bottom: 32px;
}
.admin-stat-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 20px;
  text-align: center;
}
.admin-stat-card .stat-number { font-size: 2rem; font-weight: 800; color: var(--color-primary); }
.admin-stat-card .stat-label { font-size: 0.82rem; color: var(--color-text-light); margin-top: 4px; }

.admin-table {
  width: 100%;
  border-collapse: collapse;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
}
.admin-table th, .admin-table td {
  padding: 12px 16px;
  text-align: left;
  font-size: 0.88rem;
  border-bottom: 1px solid var(--color-border-light);
}
.admin-table th { background: var(--color-bg-alt); font-weight: 600; color: var(--color-text-light); }
.admin-table tr:hover td { background: var(--color-bg-alt); }

.admin-editor {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 24px;
}
.admin-editor .form-group { margin-bottom: 16px; }
.admin-editor textarea { min-height: 200px; font-family: var(--font-mono); font-size: 0.85rem; }

.status-badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 10px;
  font-size: 0.75rem;
  font-weight: 600;
}
.status-published { background: var(--color-secondary-light); color: var(--color-secondary); }
.status-draft { background: #fef3c7; color: #92400e; }

/* ===== Admin Area on Author Page ===== */
.author-admin-area { margin-bottom: 20px; }
.author-admin-area .admin-write-btn {
  display: inline-block;
  padding: 8px 16px;
  background: var(--color-primary);
  color: #fff;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 600;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .nav-toggle { display: block; }
  .nav-list {
    display: none;
    position: absolute;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    flex-direction: column;
    padding: 16px 24px;
    box-shadow: var(--shadow-md);
  }
  .nav-list.open { display: flex; }
  .hero { padding: 48px 0 40px; }
  .hero h1 { font-size: 1.5rem; }
  .category-grid, .post-grid { grid-template-columns: 1fr; }
  .category-detail-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 24px; }
  .purpose-box, .cta-box { padding: 24px; }
  .author-mini-box { flex-direction: column; text-align: center; }
  .error-actions { flex-direction: column; align-items: center; }

  /* Admin responsive */
  .admin-sidebar { width: 200px; }
  .admin-main { margin-left: 200px; padding: 20px; }
  .admin-stats { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 480px) {
  .container { padding: 0 16px; }
  .footer-grid { grid-template-columns: 1fr; }
  .admin-sidebar { display: none; }
  .admin-main { margin-left: 0; }
}

/* ===== Structured Data (hidden) ===== */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}