/* ===========================
   CSS Variables & Reset
   =========================== */
:root {
  /* Colors */
  --color-primary: #FF9F1C;
  --color-primary-dark: #E8890A;
  --color-secondary: #2EC4B6;
  --color-secondary-dark: #25A89C;
  --color-background: #FDFFFC;
  --color-surface: #FFFFFF;
  --color-text: #1A1A2E;
  --color-text-light: #6B7280;
  --color-border: #E5E7EB;

  /* Zone Colors */
  --zone-home: #FF6B6B;
  --zone-restaurant: #FF9F1C;
  --zone-airport: #4ECDC4;
  --zone-shopping: #A78BFA;
  --zone-problem: #EF4444;
  --zone-sightseeing: #10B981;

  /* Typography */
  --font-en: 'Inter', sans-serif;
  --font-kr: 'Noto Sans KR', sans-serif;

  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;

  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 1rem;
  --radius-xl: 1.5rem;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow: 350ms ease;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-kr);
  background: var(--color-background);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ===========================
   Layout
   =========================== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

/* ===========================
   Header
   =========================== */
.header {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
  color: white;
  padding: var(--spacing-2xl) 0;
  text-align: center;
}

.header-top {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-sm);
}

.logo {
  font-family: var(--font-en);
  font-size: 2.5rem;
  font-weight: 700;
}

.admin-link {
  position: absolute;
  right: var(--spacing-lg);
  top: 50%;
  transform: translateY(-50%);
  background: rgba(255, 255, 255, 0.2);
  color: white;
  text-decoration: none;
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 500;
  transition: background var(--transition-fast);
}

.admin-link:hover {
  background: rgba(255, 255, 255, 0.3);
}

.header .container {
  position: relative;
}

.tagline {
  font-size: 1.125rem;
  opacity: 0.9;
}

/* ===========================
   Main Content
   =========================== */
.main {
  flex: 1;
  padding: var(--spacing-2xl) 0;
}

.section-title {
  font-size: 1.5rem;
  font-weight: 600;
  text-align: center;
  margin-bottom: var(--spacing-xl);
  color: var(--color-text);
}

/* ===========================
   Zones Grid
   =========================== */
.zones-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-lg);
}

.zone-card {
  background: var(--color-surface);
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-md);
  cursor: pointer;
  transition: all var(--transition-normal);
  border: 2px solid transparent;
  position: relative;
  overflow: hidden;
}

.zone-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: var(--zone-color);
}

.zone-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-xl);
  border-color: var(--zone-color);
}

.zone-icon {
  font-size: 3rem;
  margin-bottom: var(--spacing-md);
}

.zone-title {
  font-family: var(--font-en);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--spacing-xs);
}

.zone-title-kr {
  font-size: 0.875rem;
  color: var(--color-text-light);
  margin-bottom: var(--spacing-md);
}

.zone-count {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  background: var(--zone-color);
  color: white;
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-md);
  font-size: 0.75rem;
  font-weight: 500;
}

/* Zone specific colors */
.zone-card[data-zone="House Etiquette"],
.zone-card[data-zone="Culture Life"] {
  --zone-color: var(--zone-home);
}

.zone-card[data-zone="Restaurants"] {
  --zone-color: var(--zone-restaurant);
}

.zone-card[data-zone="Airport"],
.zone-card[data-zone="Foreign Airlines"] {
  --zone-color: var(--zone-airport);
}

.zone-card[data-zone="Shopping"] {
  --zone-color: var(--zone-shopping);
}

.zone-card[data-zone="Problem Solving"],
.zone-card[data-zone="Social Life"] {
  --zone-color: var(--zone-problem);
}

.zone-card[data-zone="Sightseeing"],
.zone-card[data-zone="Transportation"] {
  --zone-color: var(--zone-sightseeing);
}

/* ===========================
   Modal
   =========================== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-lg);
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-normal);
  z-index: 1000;
}

.modal-overlay.active {
  opacity: 1;
  visibility: visible;
}

.modal {
  background: var(--color-surface);
  border-radius: var(--radius-xl);
  width: 100%;
  max-width: 500px;
  max-height: 80vh;
  overflow: hidden;
  transform: scale(0.9) translateY(20px);
  transition: transform var(--transition-normal);
}

.modal-overlay.active .modal {
  transform: scale(1) translateY(0);
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-lg);
  border-bottom: 1px solid var(--color-border);
}

.modal-title {
  font-size: 1.25rem;
  font-weight: 600;
}

.modal-close {
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--color-text-light);
  line-height: 1;
  padding: var(--spacing-xs);
  transition: color var(--transition-fast);
}

.modal-close:hover {
  color: var(--color-text);
}

.modal-body {
  padding: var(--spacing-md);
  overflow-y: auto;
  max-height: calc(80vh - 80px);
}

/* ===========================
   Lesson List
   =========================== */
.lesson-list {
  list-style: none;
}

.lesson-item {
  display: block;
  padding: var(--spacing-md) var(--spacing-lg);
  border-radius: var(--radius-md);
  transition: background-color var(--transition-fast);
  text-decoration: none;
  color: var(--color-text);
  border-bottom: 1px solid var(--color-border);
}

.lesson-item:last-child {
  border-bottom: none;
}

.lesson-item:hover {
  background: #F3F4F6;
}

.lesson-topic-en {
  font-family: var(--font-en);
  font-weight: 500;
  margin-bottom: var(--spacing-xs);
}

.lesson-topic-kr {
  font-size: 0.875rem;
  color: var(--color-text-light);
}

.lesson-key-sentence {
  font-size: 0.8rem;
  color: var(--color-primary);
  margin-top: var(--spacing-xs);
  font-style: italic;
}

/* ===========================
   Footer
   =========================== */
.footer {
  background: var(--color-text);
  color: white;
  padding: var(--spacing-lg) 0;
  text-align: center;
  font-size: 0.875rem;
}

/* ===========================
   Loading State
   =========================== */
.loading {
  text-align: center;
  padding: var(--spacing-2xl);
  color: var(--color-text-light);
}

.loading::after {
  content: '';
  display: inline-block;
  width: 20px;
  height: 20px;
  border: 2px solid var(--color-border);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin-left: var(--spacing-sm);
  vertical-align: middle;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* ===========================
   Responsive
   =========================== */
/* Tablet (Galaxy Tab S7+ 등, max-width: 1024px) */
@media (max-width: 1024px) {
  .header {
    padding: var(--spacing-xl) 0;
  }
  .logo {
    font-size: 2.25rem;
  }
  .zones-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .container {
    padding: 0 var(--spacing-md);
  }
}

/* Mobile (Galaxy S22 등, max-width: 480px) */
@media (max-width: 480px) {
  .header {
    padding: var(--spacing-lg) 0;
  }
  .header-top {
    flex-direction: column;
    gap: var(--spacing-sm);
  }
  .admin-link {
    position: static;
    transform: none;
    margin-top: var(--spacing-xs);
  }
  .logo {
    font-size: 1.75rem;
  }
  .zones-grid {
    grid-template-columns: 1fr;
  }
  .zone-card {
    padding: var(--spacing-md);
  }
  .zone-icon {
    font-size: 2.5rem;
  }
  .tagline {
    font-size: 0.9rem;
  }
}