/* ============================================
   My Chatbot World - Design System
   ============================================ */

/* === Google Fonts === */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&display=swap');

/* === CSS Variables === */
:root {
  /* Primary Colors */
  --primary-50: #eef2ff;
  --primary-100: #e0e7ff;
  --primary-200: #c7d2fe;
  --primary-300: #a5b4fc;
  --primary-400: #818cf8;
  --primary-500: #6366f1;
  --primary-600: #4f46e5;
  --primary-700: #4338ca;
  --primary-800: #3730a3;
  --primary-900: #312e81;

  /* Accent */
  --accent-400: #a78bfa;
  --accent-500: #8b5cf6;
  --accent-600: #7c3aed;

  /* Success / Warning / Error */
  --success-500: #22c55e;
  --warning-500: #f59e0b;
  --error-500: #ef4444;

  /* Neutrals */
  --gray-50: #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-300: #d1d5db;
  --gray-400: #9ca3af;
  --gray-500: #6b7280;
  --gray-600: #4b5563;
  --gray-700: #374151;
  --gray-800: #1f2937;
  --gray-900: #111827;

  /* Gradients */
  --gradient-primary: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #a78bfa 100%);
  --gradient-dark: linear-gradient(135deg, #1e1b4b 0%, #312e81 50%, #3730a3 100%);
  --gradient-hero: linear-gradient(135deg, #0f0c29 0%, #302b63 50%, #24243e 100%);
  --gradient-card: linear-gradient(145deg, rgba(255,255,255,0.05) 0%, rgba(255,255,255,0.02) 100%);
  --gradient-glow: radial-gradient(600px circle at var(--mouse-x, 50%) var(--mouse-y, 50%), rgba(99, 102, 241, 0.15), transparent 40%);

  /* 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 -2px rgba(0,0,0,0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -4px rgba(0,0,0,0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 8px 10px -6px rgba(0,0,0,0.1);
  --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.3);
  --shadow-glow-lg: 0 0 80px rgba(99, 102, 241, 0.2);

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  --font-size-5xl: 3rem;
  --font-size-6xl: 3.75rem;
  --font-size-7xl: 4.5rem;

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --radius-full: 9999px;

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-spring: 500ms cubic-bezier(0.34, 1.56, 0.64, 1);
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

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

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

input, textarea, select {
  font-family: inherit;
  font-size: inherit;
}

/* === Utility Classes === */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.container-sm {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.text-center { text-align: center; }
.text-left { text-align: left; }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: var(--space-2); }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }
.gap-8 { gap: var(--space-8); }

.grid { display: grid; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

/* === Buttons === */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius-xl);
  font-weight: 600;
  font-size: var(--font-size-base);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(255,255,255,0);
  transition: background var(--transition-fast);
}

.btn:hover::before {
  background: rgba(255,255,255,0.1);
}

.btn:active {
  transform: scale(0.97);
}

.btn-primary {
  background: var(--gradient-primary);
  color: white;
  box-shadow: var(--shadow-md), 0 0 20px rgba(99, 102, 241, 0.2);
}

.btn-primary:hover {
  box-shadow: var(--shadow-lg), 0 0 30px rgba(99, 102, 241, 0.3);
  transform: translateY(-2px);
}

.btn-secondary {
  background: rgba(255,255,255, 0.1);
  color: white;
  border: 1px solid rgba(255,255,255, 0.2);
  backdrop-filter: blur(10px);
}

.btn-secondary:hover {
  background: rgba(255,255,255, 0.2);
  border-color: rgba(255,255,255, 0.3);
  transform: translateY(-2px);
}

.btn-outline {
  background: transparent;
  color: var(--primary-600);
  border: 2px solid var(--primary-200);
}

.btn-outline:hover {
  background: var(--primary-50);
  border-color: var(--primary-400);
  transform: translateY(-2px);
}

.btn-lg {
  padding: var(--space-4) var(--space-8);
  font-size: var(--font-size-lg);
  border-radius: var(--radius-2xl);
}

.btn-xl {
  padding: var(--space-5) var(--space-10);
  font-size: var(--font-size-xl);
  border-radius: var(--radius-2xl);
}

.btn-sm {
  padding: var(--space-2) var(--space-4);
  font-size: var(--font-size-sm);
}

.btn-icon {
  width: 40px;
  height: 40px;
  padding: 0;
  border-radius: var(--radius-full);
}

/* === Cards === */
.card {
  background: white;
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--gray-100);
  transition: all var(--transition-base);
}

.card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-4px);
}

.card-dark {
  background: rgba(255,255,255, 0.05);
  border: 1px solid rgba(255,255,255, 0.1);
  backdrop-filter: blur(10px);
  color: white;
}

.card-dark:hover {
  background: rgba(255,255,255, 0.08);
  border-color: rgba(255,255,255, 0.15);
  box-shadow: var(--shadow-glow);
}

/* === Badges === */
.badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-full);
  font-size: var(--font-size-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.badge-primary {
  background: var(--primary-100);
  color: var(--primary-700);
}

.badge-success {
  background: #dcfce7;
  color: #166534;
}

.badge-accent {
  background: rgba(139, 92, 246, 0.15);
  color: var(--accent-500);
}

/* === Section Titles === */
.section-title {
  font-size: var(--font-size-4xl);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: var(--space-4);
  letter-spacing: -0.02em;
}

.section-subtitle {
  font-size: var(--font-size-lg);
  color: var(--gray-500);
  max-width: 600px;
  margin: 0 auto;
  line-height: 1.7;
}

/* === Animations === */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(30px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideInLeft {
  from { opacity: 0; transform: translateX(-30px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes float {
  0%, 100% { transform: translateY(0px); }
  50% { transform: translateY(-10px); }
}

@keyframes pulse-glow {
  0%, 100% { box-shadow: 0 0 20px rgba(99, 102, 241, 0.3); }
  50% { box-shadow: 0 0 40px rgba(99, 102, 241, 0.5); }
}

@keyframes shimmer {
  0% { background-position: -200% 0; }
  100% { background-position: 200% 0; }
}

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

@keyframes bounceIn {
  0% { opacity: 0; transform: scale(0.3); }
  50% { opacity: 1; transform: scale(1.05); }
  70% { transform: scale(0.9); }
  100% { transform: scale(1); }
}

.animate-fadeInUp { animation: fadeInUp 0.6s ease-out forwards; }
.animate-fadeIn { animation: fadeIn 0.4s ease-out forwards; }
.animate-float { animation: float 3s ease-in-out infinite; }
.animate-pulse-glow { animation: pulse-glow 2s ease-in-out infinite; }

.delay-100 { animation-delay: 0.1s; }
.delay-200 { animation-delay: 0.2s; }
.delay-300 { animation-delay: 0.3s; }
.delay-400 { animation-delay: 0.4s; }
.delay-500 { animation-delay: 0.5s; }

/* === Navbar === */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: var(--space-4) 0;
  transition: all var(--transition-base);
}

.navbar.scrolled {
  background: rgba(15, 12, 41, 0.95);
  backdrop-filter: blur(20px);
  padding: var(--space-3) 0;
  box-shadow: 0 1px 20px rgba(0,0,0,0.3);
}

.navbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.navbar-logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--font-size-xl);
  font-weight: 800;
  color: white;
}

.navbar-logo span {
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.navbar-links {
  display: flex;
  align-items: center;
  gap: var(--space-8);
  list-style: none;
}

.navbar-links a {
  color: rgba(255,255,255,0.7);
  font-size: var(--font-size-sm);
  font-weight: 500;
  transition: color var(--transition-fast);
}

.navbar-links a.nav-menu-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  line-height: 1.2;
}

.navbar-links .nav-en {
  font-size: var(--font-size-sm);
  font-weight: 600;
}

.navbar-links .nav-ko {
  font-size: 0.7rem;
  opacity: 0.55;
  margin-top: 2px;
}

.navbar-links a:hover {
  color: white;
}

.navbar-cta .btn {
  padding: var(--space-2) var(--space-5);
  font-size: var(--font-size-sm);
}

/* === Form Elements === */
.form-group {
  margin-bottom: var(--space-5);
}

.form-label {
  display: block;
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--gray-700);
  margin-bottom: var(--space-2);
}

.form-input {
  width: 100%;
  padding: var(--space-3) var(--space-4);
  border: 2px solid var(--gray-200);
  border-radius: var(--radius-lg);
  font-size: var(--font-size-base);
  transition: all var(--transition-fast);
  outline: none;
  background: white;
}

.form-input:focus {
  border-color: var(--primary-400);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.form-textarea {
  resize: vertical;
  min-height: 100px;
}

/* === Toast / Notification === */
.toast {
  position: fixed;
  bottom: var(--space-6);
  right: var(--space-6);
  padding: var(--space-4) var(--space-6);
  background: var(--gray-900);
  color: white;
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-xl);
  z-index: 9999;
  animation: fadeInUp 0.3s ease-out;
  font-weight: 500;
}

/* === Loading Spinner === */
.spinner {
  width: 24px;
  height: 24px;
  border: 3px solid rgba(255,255,255,0.2);
  border-top-color: white;
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
}

.spinner-primary {
  border-color: var(--primary-100);
  border-top-color: var(--primary-500);
}

/* === Responsive === */
@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  :root { font-size: 15px; }
  .container { padding: 0 var(--space-4); }
  .grid-4, .grid-3, .grid-2 { grid-template-columns: 1fr; }
  .section-title { font-size: var(--font-size-3xl); }
  .navbar-links { display: none; }

  .btn-xl {
    padding: var(--space-4) var(--space-6);
    font-size: var(--font-size-base);
  }
}

@media (max-width: 480px) {
  :root { font-size: 14px; }
}