/* ===== Google Fonts ===== */
@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+KR:wght@300;400;500;600;700;900&display=swap');

/* ===== CSS Variables ===== */
:root {
  --primary: #1e3a8a;
  --primary-light: #3b82f6;
  --primary-dark: #1e2d5f;
  --secondary: #10b981;
  --secondary-light: #34d399;
  --danger: #ef4444;
  --warning: #f59e0b;
  --info: #06b6d4;

  --bg: #ffffff;
  --bg-alt: #f8fafc;
  --bg-card: #ffffff;
  --text: #1e293b;
  --text-light: #64748b;
  --text-muted: #94a3b8;
  --border: #e2e8f0;
  --border-light: #f1f5f9;

  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2rem;
  --space-xl: 3rem;
  --space-2xl: 4rem;

  --radius: 12px;
  --radius-sm: 8px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --radius-full: 9999px;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow: 0 1px 3px rgba(0,0,0,0.1), 0 1px 2px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.07), 0 2px 4px rgba(0,0,0,0.06);
  --shadow-lg: 0 10px 25px rgba(0,0,0,0.1);
  --shadow-xl: 0 20px 40px rgba(0,0,0,0.12);

  --font: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --transition: 0.2s ease;
  --max-width: 1200px;
}

/* ===== Dark Mode ===== */
[data-theme="dark"] {
  --bg: #0f172a;
  --bg-alt: #1e293b;
  --bg-card: #1e293b;
  --text: #f1f5f9;
  --text-light: #94a3b8;
  --text-muted: #64748b;
  --border: #334155;
  --border-light: #1e293b;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
  --shadow: 0 1px 3px rgba(0,0,0,0.4);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.4);
  --shadow-lg: 0 10px 25px rgba(0,0,0,0.5);
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font);
  color: var(--text);
  background: var(--bg-alt);
  line-height: 1.7;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

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

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

/* ===== Header ===== */
.site-header {
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: var(--shadow-sm);
  backdrop-filter: blur(8px);
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0.75rem var(--space-md);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--primary);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.logo:hover { color: var(--primary-light); }
.logo-icon { font-size: 1.5rem; }

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}
.nav-links > a {
  color: var(--text-light);
  font-size: 0.9rem;
  font-weight: 500;
  transition: color var(--transition);
  padding: 0.5rem 0.65rem;
}
.nav-links > a:hover { color: var(--primary); }

/* ===== Nav Item (dropdown wrapper) ===== */
.nav-item {
  position: relative;
}
.nav-item > .nav-link {
  color: var(--text-light);
  font-size: 0.9rem;
  font-weight: 500;
  padding: 0.5rem 0.65rem;
  cursor: pointer;
  transition: color var(--transition);
  display: flex;
  align-items: center;
  gap: 0.25rem;
  white-space: nowrap;
  text-decoration: none;
}
.nav-item > .nav-link:hover { color: var(--primary); }
.nav-item > .nav-link .arrow {
  font-size: 0.6rem;
  transition: transform 0.2s ease;
}

/* ===== Dropdown Panel ===== */
.nav-dropdown {
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%) translateY(8px);
  min-width: 200px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  visibility: hidden;
  transition: all 0.2s ease;
  z-index: 1001;
  padding: 0.5rem 0;
}
.nav-item:hover > .nav-dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}
.nav-item:hover > .nav-link .arrow {
  transform: rotate(180deg);
}
.nav-dropdown a {
  display: block;
  padding: 0.5rem 1rem;
  color: var(--text-light);
  font-size: 0.85rem;
  font-weight: 400;
  transition: all var(--transition);
  white-space: nowrap;
  text-decoration: none;
}
.nav-dropdown a:hover {
  background: var(--bg-alt);
  color: var(--primary);
  padding-left: 1.25rem;
}

.dark-toggle {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  padding: 0.5rem 0.75rem;
  cursor: pointer;
  font-size: 1.1rem;
  transition: all var(--transition);
  display: flex;
  align-items: center;
}
.dark-toggle:hover { background: var(--border); }

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text);
  padding: 0.25rem;
}

/* ===== Main Content ===== */
.main-content {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-xl) var(--space-md);
}

/* ===== Hero Section (index) ===== */
.hero {
  text-align: center;
  padding: var(--space-2xl) var(--space-md);
}
.hero h1 {
  font-size: 2.5rem;
  font-weight: 900;
  color: var(--primary);
  margin-bottom: var(--space-sm);
  line-height: 1.3;
}
.hero .subtitle {
  font-size: 1.15rem;
  color: var(--text-light);
  max-width: 600px;
  margin: 0 auto var(--space-lg);
}

/* ===== Search Bar ===== */
.search-container {
  max-width: 500px;
  margin: 0 auto var(--space-xl);
  position: relative;
}
.search-input {
  width: 100%;
  padding: 1rem 1rem 1rem 3rem;
  border: 2px solid var(--border);
  border-radius: var(--radius-full);
  font-size: 1rem;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  transition: all var(--transition);
  box-shadow: var(--shadow-sm);
}
.search-input:focus {
  outline: none;
  border-color: var(--primary-light);
  box-shadow: 0 0 0 3px rgba(59,130,246,0.15);
}
.search-icon {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  font-size: 1.1rem;
}

/* ===== Category Tabs ===== */
.category-tabs {
  display: flex;
  gap: 0.5rem;
  margin-bottom: var(--space-xl);
  overflow-x: auto;
  padding-bottom: 0.5rem;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}
.category-tabs::-webkit-scrollbar { display: none; }

.tab-btn {
  padding: 0.6rem 1.2rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  background: var(--bg);
  color: var(--text-light);
  font-size: 0.875rem;
  font-weight: 500;
  font-family: var(--font);
  cursor: pointer;
  white-space: nowrap;
  transition: all var(--transition);
}
.tab-btn:hover {
  border-color: var(--primary-light);
  color: var(--primary);
}
.tab-btn.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

/* ===== Calculator Card Grid ===== */
.calc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-md);
}

.calc-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  text-decoration: none;
  color: var(--text);
  transition: all var(--transition);
  display: flex;
  flex-direction: column;
  position: relative;
  overflow: hidden;
}
.calc-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--primary), var(--primary-light));
  opacity: 0;
  transition: opacity var(--transition);
}
.calc-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary-light);
}
.calc-card:hover::before { opacity: 1; }

.calc-card .card-icon {
  font-size: 2rem;
  margin-bottom: var(--space-sm);
}
.calc-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.4rem;
  color: var(--text);
}
.calc-card p {
  font-size: 0.85rem;
  color: var(--text-light);
  line-height: 1.5;
  flex: 1;
}
.calc-card .card-tag {
  display: inline-block;
  margin-top: var(--space-sm);
  padding: 0.2rem 0.6rem;
  background: var(--bg-alt);
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* ===== Footer ===== */
.site-footer {
  background: var(--bg);
  border-top: 1px solid var(--border);
  padding: var(--space-xl) var(--space-md);
  margin-top: var(--space-2xl);
}
.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  text-align: center;
}
.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--space-md);
  margin-bottom: var(--space-sm);
  flex-wrap: wrap;
}
.footer-links a {
  color: var(--text-light);
  font-size: 0.875rem;
}
.footer-links a:hover { color: var(--primary); }

.footer-copy {
  color: var(--text-muted);
  font-size: 0.8rem;
  margin-bottom: 0.3rem;
}
.footer-disclaimer {
  color: var(--text-muted);
  font-size: 0.75rem;
  padding-top: var(--space-sm);
  border-top: 1px solid var(--border);
  margin-top: var(--space-sm);
}

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

.hidden { display: none !important; }

/* ===== Ad Slots ===== */
.ad-slot {
  background: var(--bg-alt);
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  padding: var(--space-md);
  text-align: center;
  color: var(--text-muted);
  font-size: 0.8rem;
  margin: var(--space-lg) 0;
  min-height: 90px;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .hero h1 { font-size: 1.75rem; }
  .hero .subtitle { font-size: 1rem; }

  .nav-links { display: none; }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    padding: var(--space-xs) 0;
    box-shadow: var(--shadow-md);
    gap: 0;
    max-height: 80vh;
    overflow-y: auto;
  }
  .nav-links.open > a {
    padding: 0.75rem var(--space-md);
  }
  .mobile-menu-btn { display: block; }

  /* Mobile dropdown accordion */
  .nav-item > .nav-link {
    padding: 0.75rem var(--space-md);
    justify-content: space-between;
  }
  .nav-dropdown {
    position: static;
    transform: none;
    min-width: 0;
    opacity: 1;
    visibility: visible;
    box-shadow: none;
    border: none;
    border-radius: 0;
    background: var(--bg-alt);
    display: none;
    padding: 0;
    transition: none;
  }
  .nav-item:hover > .nav-dropdown {
    transform: none;
    display: none;
  }
  .nav-item.open > .nav-dropdown {
    display: block;
  }
  .nav-item.open > .nav-link .arrow {
    transform: rotate(180deg);
  }
  .nav-dropdown a {
    padding: 0.6rem var(--space-md) 0.6rem calc(var(--space-md) + 1rem);
    font-size: 0.85rem;
  }
  .nav-dropdown a:hover {
    padding-left: calc(var(--space-md) + 1.25rem);
  }

  .calc-grid {
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: var(--space-sm);
  }
  .calc-card { padding: var(--space-md); }

  .main-content { padding: var(--space-lg) var(--space-sm); }
  .hero { padding: var(--space-lg) var(--space-sm); }
}

@media (max-width: 480px) {
  .calc-grid { grid-template-columns: 1fr; }
  .hero h1 { font-size: 1.5rem; }
  .category-tabs { gap: 0.3rem; }
  .tab-btn { padding: 0.5rem 0.9rem; font-size: 0.8rem; }
}