/* ============================================
   WHK Blog Detail - World-Class Design System
   ============================================ */

:root {
  /* Brand Colors */
  --whk-navy: #0d1321;
  --whk-navy-light: #1a2332;
  --whk-blue: #2563eb;
  --whk-blue-dark: #1d4ed8;
  --whk-cyan: #06b6d4;
  --whk-accent: #4264D1;

  /* Neutrals */
  --gray-50: #f8fafc;
  --gray-100: #f1f5f9;
  --gray-200: #e2e8f0;
  --gray-300: #cbd5e1;
  --gray-400: #94a3b8;
  --gray-500: #64748b;
  --gray-600: #475569;
  --gray-700: #334155;
  --gray-800: #1e293b;
  --gray-900: #0f172a;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-serif: 'Playfair Display', Georgia, serif;

  /* Spacing */
  --container-max: 1280px;
  --content-max: 840px;
  --sidebar-width: 280px;

  /* Effects */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: var(--gray-50);
  color: var(--gray-800);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ============================================
   Navigation
   ============================================ */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--gray-200);
  transition: all 0.3s ease;
}

.nav.scrolled {
  box-shadow: var(--shadow-md);
}

.nav-container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
  height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  display: flex;
  align-items: center;
}

.nav-logo img {
  height: 40px;
  width: auto;
  display: block;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}

.nav-links a {
  color: var(--gray-600);
  text-decoration: none;
  font-size: 15px;
  font-weight: 500;
  transition: color 0.2s;
}

.nav-links a:hover {
  color: var(--whk-blue);
}

.nav-cta {
  background: var(--whk-navy);
  color: white !important;
  padding: 10px 20px;
  border-radius: 8px;
  font-weight: 600;
  transition: all 0.2s;
}

.nav-cta:hover {
  background: var(--gray-800);
  transform: translateY(-1px);
}

.nav-mobile-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

.nav-mobile-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--gray-700);
  margin: 5px 0;
  transition: 0.3s;
}

/* Mobile Menu Overlay */
.nav-mobile-menu {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 999;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s ease, visibility 0.3s ease;
}

.nav-mobile-menu.active {
  opacity: 1;
  visibility: visible;
}

.nav-mobile-menu-backdrop {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(4px);
}

.nav-mobile-menu-content {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  width: 80%;
  max-width: 320px;
  background: white;
  box-shadow: -4px 0 24px rgba(0, 0, 0, 0.15);
  transform: translateX(100%);
  transition: transform 0.3s ease;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
}

.nav-mobile-menu.active .nav-mobile-menu-content {
  transform: translateX(0);
}

.nav-mobile-close {
  align-self: flex-end;
  background: none;
  border: none;
  font-size: 32px;
  line-height: 1;
  color: var(--gray-700);
  cursor: pointer;
  padding: 16px 24px;
  transition: color 0.2s;
}

.nav-mobile-close:hover {
  color: var(--gray-900);
}

.nav-mobile-links {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
}

.nav-mobile-links li {
  border-bottom: 1px solid var(--gray-200);
}

.nav-mobile-links a {
  display: block;
  padding: 16px 24px;
  color: var(--gray-700);
  text-decoration: none;
  font-size: 16px;
  font-weight: 500;
  transition: all 0.2s;
}

.nav-mobile-links a:hover {
  background: var(--gray-50);
  color: var(--whk-blue);
}

.nav-mobile-cta {
  background: var(--whk-navy) !important;
  color: white !important;
  margin: 16px 24px;
  border-radius: 8px;
  text-align: center;
}

.nav-mobile-cta:hover {
  background: var(--gray-800) !important;
  color: white !important;
}

/* Mobile ToC inside the slide-in menu */
.nav-mobile-toc {
  margin-top: 8px;
  padding: 8px 0 24px;
  border-top: 1px solid var(--gray-200);
}

.nav-mobile-toc-title {
  font-size: 12px;
  font-weight: 700;
  color: var(--gray-400);
  text-transform: uppercase;
  letter-spacing: 1px;
  padding: 16px 24px 8px;
}

.nav-mobile-menu-content .toc-list {
  border-left: none;
}

.nav-mobile-menu-content .toc-item a {
  padding: 12px 24px;
  margin-left: 0;
  border-left: none;
  font-size: 15px;
}

.nav-mobile-menu-content .toc-item.active>a,
.nav-mobile-menu-content .toc-item.active-parent>a {
  border-left: none;
}

.nav-mobile-menu-content .toc-toggle {
  right: 16px;
}

.nav-mobile-menu-content .toc-sublist {
  padding-left: 0;
}

.nav-mobile-menu-content .toc-sublist a {
  padding: 10px 24px;
}

/* Prevent body scroll when menu is open */
body.menu-open {
  overflow: hidden;
}