/* ==========================================================================
   Project OmniCalc - Global Design System & Variables
   High-performance, Modern Glassmorphism & Dual Theme (Dark / Light)
   ========================================================================== */

:root {
  /* Multi-language toggle classes */
}

html[lang="ko"] .lang-en {
  display: none !important;
}

html[lang="en"] .lang-ko {
  display: none !important;
}

:root {
  /* Color Tokens - Light Mode */
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f1f5f9;
  --bg-elevated: rgba(255, 255, 255, 0.85);
  --bg-glass: rgba(255, 255, 255, 0.7);
  --border-color: #e2e8f0;
  --border-subtle: #edf2f7;

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --text-inverse: #ffffff;

  --accent-primary: #4f46e5;
  --accent-primary-hover: #4338ca;
  --accent-primary-light: #eef2ff;
  --accent-blue: #2563eb;
  --accent-cyan: #06b6d4;
  --accent-green: #10b981;
  --accent-amber: #f59e0b;
  --accent-rose: #f43f5e;

  /* Calculator Keypad Colors - Light Mode */
  --key-num-bg: #ffffff;
  --key-num-text: #1e293b;
  --key-num-hover: #f8fafc;
  --key-fn-bg: #f1f5f9;
  --key-fn-text: #334155;
  --key-fn-hover: #e2e8f0;
  --key-op-bg: #e0e7ff;
  --key-op-text: #4338ca;
  --key-op-hover: #c7d2fe;
  --key-equal-bg: #4f46e5;
  --key-equal-text: #ffffff;
  --key-equal-hover: #4338ca;
  --key-danger-bg: #ffe4e6;
  --key-danger-text: #e11d48;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Pretendard', sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', Consolas, Menlo, monospace;

  /* Shadow & Blur */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.08), 0 2px 4px -2px rgb(0 0 0 / 0.06);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.08), 0 4px 6px -4px rgb(0 0 0 / 0.04);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.05);
  --shadow-glow: 0 0 20px rgba(79, 70, 229, 0.2);

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 250ms cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  /* Color Tokens - Deep Space Dark Mode */
  --bg-primary: #0b0f19;
  --bg-secondary: #111827;
  --bg-tertiary: #1f2937;
  --bg-elevated: rgba(17, 24, 39, 0.85);
  --bg-glass: rgba(17, 24, 39, 0.7);
  --border-color: #273549;
  --border-subtle: #1e293b;

  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --text-inverse: #0b0f19;

  --accent-primary: #6366f1;
  --accent-primary-hover: #4f46e5;
  --accent-primary-light: rgba(99, 102, 241, 0.15);
  --accent-blue: #3b82f6;
  --accent-cyan: #22d3ee;
  --accent-green: #34d399;
  --accent-amber: #fbbf24;
  --accent-rose: #fb7185;

  /* Calculator Keypad Colors - Dark Mode */
  --key-num-bg: #1e293b;
  --key-num-text: #f8fafc;
  --key-num-hover: #334155;
  --key-fn-bg: #151e2e;
  --key-fn-text: #94a3b8;
  --key-fn-hover: #1e293b;
  --key-op-bg: #1e1b4b;
  --key-op-text: #a5b4fc;
  --key-op-hover: #312e81;
  --key-equal-bg: #6366f1;
  --key-equal-text: #ffffff;
  --key-equal-hover: #4f46e5;
  --key-danger-bg: #4c0519;
  --key-danger-text: #fda4af;

  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.5);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.4);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.5);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.6);
  --shadow-glow: 0 0 25px rgba(99, 102, 241, 0.3);
}

/* Base Reset & Typography */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  font-feature-settings: 'cv02', 'cv03', 'cv04', 'cv11';
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background-color var(--transition-normal), color var(--transition-normal);
  background-image: 
    radial-gradient(at 100% 0%, rgba(99, 102, 241, 0.08) 0px, transparent 50%),
    radial-gradient(at 0% 100%, rgba(59, 130, 246, 0.06) 0px, transparent 50%);
  background-attachment: fixed;
}

a {
  color: inherit;
  text-decoration: none;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  outline: none;
}

/* Layout Utilities */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.25rem;
}

/* Global Header & Nav */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background-color: var(--bg-elevated);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  transition: border-color var(--transition-normal);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  font-weight: 700;
  font-size: 1.25rem;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

.logo-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-blue));
  color: #ffffff;
  font-size: 1rem;
  font-weight: 800;
  box-shadow: 0 2px 8px rgba(79, 70, 229, 0.35);
}

.brand-name {
  background: linear-gradient(135deg, var(--text-primary) 70%, var(--accent-primary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  list-style: none;
}

.nav-item a {
  display: inline-flex;
  align-items: center;
  padding: 0.5rem 0.85rem;
  border-radius: var(--radius-sm);
  font-size: 0.925rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.nav-item a:hover {
  color: var(--text-primary);
  background-color: var(--bg-tertiary);
}

.nav-item.active a {
  color: var(--accent-primary);
  background-color: var(--accent-primary-light);
  font-weight: 600;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.btn-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
  background-color: var(--bg-secondary);
  transition: all var(--transition-fast);
}

.btn-icon:hover {
  color: var(--text-primary);
  border-color: var(--accent-primary);
  box-shadow: var(--shadow-sm);
  transform: translateY(-1px);
}

.lang-selector {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.35rem 0.65rem;
  height: 38px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.lang-selector:hover {
  border-color: var(--accent-primary);
}

/* Mobile Navigation Hamburger */
.mobile-nav-toggle {
  display: none;
  font-size: 1.25rem;
}

/* Main Layout Grid */
.main-wrapper {
  flex: 1;
  padding: 2rem 0 3.5rem;
}

.page-hero {
  text-align: center;
  margin-bottom: 2rem;
}

.page-hero h1 {
  font-size: 2.25rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: 0.5rem;
  line-height: 1.2;
}

.page-hero p {
  color: var(--text-secondary);
  font-size: 1.05rem;
  max-width: 640px;
  margin: 0 auto;
}

/* Quick Tools Grid */
.tools-nav-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
  margin-bottom: 2rem;
}

.tool-card {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1rem 1.25rem;
  border-radius: var(--radius-lg);
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
}

.tool-card:hover {
  border-color: var(--accent-primary);
  box-shadow: var(--shadow-md), var(--shadow-glow);
  transform: translateY(-2px);
}

.tool-card.active {
  border-color: var(--accent-primary);
  background: linear-gradient(135deg, var(--bg-secondary), var(--accent-primary-light));
}

.tool-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  font-size: 1.35rem;
  background-color: var(--accent-primary-light);
  color: var(--accent-primary);
  flex-shrink: 0;
}

.tool-info h3 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.15rem;
}

.tool-info p {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* Global Footer */
.site-footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 3rem 0 2rem;
  margin-top: auto;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 2.5rem;
  margin-bottom: 2.5rem;
}

.footer-col h4 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 1rem;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.footer-links a {
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

.footer-links a:hover {
  color: var(--accent-primary);
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border-color);
  font-size: 0.825rem;
  color: var(--text-muted);
}

.footer-admin-link {
  color: var(--text-muted);
  font-size: 0.75rem;
  opacity: 0.5;
  transition: opacity var(--transition-fast);
}

.footer-admin-link:hover {
  opacity: 1;
  color: var(--accent-primary);
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 1000;
  display: flex;
  flex-direction: column;
  gap: 8px;
  pointer-events: none;
}

.toast {
  pointer-events: auto;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 12px 18px;
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  border-left: 4px solid var(--accent-primary);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  font-size: 0.9rem;
  font-weight: 500;
  animation: toastSlideUp 0.3s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

@keyframes toastSlideUp {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* AdSense Slot Placeholders (CLS Zero Guaranteed) */
.ad-slot-container {
  margin: 1.5rem auto;
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100%;
  overflow: hidden;
}

.ad-slot {
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--bg-tertiary);
  border: 1px dashed var(--border-color);
  border-radius: var(--radius-md);
  color: var(--text-muted);
  font-size: 0.75rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

/* Specific Standard Ad Dimensions */
.ad-slot-leaderboard {
  min-height: 90px;
  width: 728px;
  max-width: 100%;
}

.ad-slot-rectangle {
  min-height: 250px;
  width: 300px;
  max-width: 100%;
}

.ad-slot-banner {
  min-height: 60px;
  width: 100%;
  max-width: 728px;
}

/* Responsive Media Queries */
@media (max-width: 900px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
  }
  .mobile-nav-toggle {
    display: inline-flex;
  }
  .page-hero h1 {
    font-size: 1.75rem;
  }
  .tools-nav-grid {
    grid-template-columns: 1fr 1fr;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .footer-bottom {
    flex-direction: column;
    gap: 0.75rem;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .tools-nav-grid {
    grid-template-columns: 1fr;
  }
}