/* ==========================================================================
   AI Edumate Intro Landing Page Styles (intro.css)
   ========================================================================== */

:root {
  /* Theme Colors - Light Mode (Default) */
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-alt: #f1f5f9;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --border-color: rgba(226, 232, 240, 0.8);

  --accent-purple: #8b5cf6;
  --accent-purple-glow: rgba(139, 92, 246, 0.3);
  --accent-blue: #3b82f6;
  --accent-green: #10b981;
  --accent-orange: #f59e0b;

  --glass-bg: rgba(255, 255, 255, 0.75);
  --glass-border: rgba(255, 255, 255, 0.5);
  --glass-shadow: 0 20px 40px -15px rgba(0, 0, 0, 0.05);

  --card-bg: rgba(255, 255, 255, 0.9);
  --card-border: rgba(226, 232, 240, 0.8);
  --card-hover-shadow: 0 12px 30px -10px rgba(139, 92, 246, 0.15);

  --header-bg: rgba(248, 250, 252, 0.85);
  --font-family: 'Outfit', 'Noto Sans KR', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
}

[data-theme="dark"] {
  /* Theme Colors - Dark Mode */
  --bg-primary: #0b0f19;
  --bg-secondary: #111827;
  --bg-alt: #161f32;
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --border-color: rgba(255, 255, 255, 0.1);

  --glass-bg: rgba(17, 24, 39, 0.75);
  --glass-border: rgba(255, 255, 255, 0.12);
  --glass-shadow: 0 20px 40px -15px rgba(0, 0, 0, 0.5);

  --card-bg: rgba(17, 24, 39, 0.85);
  --card-border: rgba(255, 255, 255, 0.08);
  --card-hover-shadow: 0 15px 35px -10px rgba(139, 92, 246, 0.3);

  --header-bg: rgba(11, 15, 25, 0.85);
}

/* Global Reset & Typography */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
  transition: background-color 0.3s ease, color 0.3s ease;
}

/* Common Container & Gradient Text */
.gradient-text {
  background: linear-gradient(135deg, #a855f7 0%, #3b82f6 50%, #06b6d4 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Top Navigation Bar */
.intro-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 72px;
  background-color: var(--header-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
}

.intro-nav-container {
  max-width: 1240px;
  margin: 0 auto;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
}

.brand-link {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--text-primary);
}

.brand-logo img {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  object-fit: contain;
}

.brand-title {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.5px;
}

.brand-badge {
  background: linear-gradient(135deg, var(--accent-purple), var(--accent-blue));
  color: #ffffff;
  font-size: 0.7rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 20px;
  text-transform: uppercase;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
}

.nav-item {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  transition: color 0.2s ease;
}

.nav-item:hover {
  color: var(--accent-purple);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 14px;
}

/* Language Toggle Segment Control */
.lang-toggle-container {
  display: flex;
  background: var(--bg-alt);
  padding: 3px;
  border-radius: 20px;
  border: 1px solid var(--border-color);
}

.lang-toggle-btn {
  background: none;
  border: none;
  color: var(--text-secondary);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 16px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 4px;
  transition: all 0.2s ease;
}

.lang-toggle-btn.active {
  background: var(--accent-purple);
  color: #ffffff;
  box-shadow: 0 2px 8px rgba(139, 92, 246, 0.4);
}

/* Theme Toggle Button */
.btn-theme-toggle {
  background: var(--bg-alt);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  width: 38px;
  height: 38px;
  border-radius: 12px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.05rem;
  transition: all 0.2s ease;
}

.btn-theme-toggle:hover {
  border-color: var(--accent-purple);
  color: var(--accent-purple);
}

/* Primary CTA Button */
.btn-primary-cta {
  background: linear-gradient(135deg, var(--accent-purple), var(--accent-blue));
  color: #ffffff;
  text-decoration: none;
  padding: 10px 20px;
  border-radius: 12px;
  font-size: 0.92rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 8px;
  box-shadow: 0 4px 16px rgba(139, 92, 246, 0.35);
  transition: all 0.25 ease;
}

.btn-primary-cta:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(139, 92, 246, 0.5);
}

/* Hero Section */
.intro-hero {
  position: relative;
  padding: 160px 24px 100px;
  text-align: center;
  overflow: hidden;
}

.hero-glow-effect {
  position: absolute;
  top: 10%;
  left: 50%;
  transform: translateX(-50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(139, 92, 246, 0.2) 0%, rgba(59, 130, 246, 0.1) 40%, transparent 70%);
  filter: blur(80px);
  z-index: 0;
  pointer-events: none;
}

.hero-container {
  position: relative;
  max-width: 960px;
  margin: 0 auto;
  z-index: 1;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  background: rgba(139, 92, 246, 0.12);
  border: 1px solid rgba(139, 92, 246, 0.3);
  border-radius: 30px;
  color: var(--accent-purple);
  font-size: 0.88rem;
  font-weight: 600;
  margin-bottom: 24px;
}

.hero-headline {
  font-size: 3.2rem;
  font-weight: 800;
  line-height: 1.25;
  letter-spacing: -1px;
  margin-bottom: 20px;
}

.hero-subheadline {
  font-size: 1.2rem;
  color: var(--text-secondary);
  max-width: 760px;
  margin: 0 auto 36px;
  line-height: 1.7;
}

.hero-cta-group {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  margin-bottom: 60px;
}

.btn-hero-primary {
  background: linear-gradient(135deg, var(--accent-purple), var(--accent-blue));
  color: #ffffff;
  text-decoration: none;
  padding: 14px 32px;
  border-radius: 14px;
  font-size: 1.05rem;
  font-weight: 700;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  box-shadow: 0 10px 30px rgba(139, 92, 246, 0.4);
  transition: all 0.3s ease;
}

.btn-hero-primary:hover {
  transform: translateY(-3px);
  box-shadow: 0 15px 35px rgba(139, 92, 246, 0.6);
}

.btn-hero-secondary {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  text-decoration: none;
  padding: 14px 28px;
  border-radius: 14px;
  font-size: 1rem;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  transition: all 0.3s ease;
}

.btn-hero-secondary:hover {
  border-color: var(--accent-purple);
  color: var(--accent-purple);
}

/* Feature Visual Preview Card */
.hero-visual-card {
  max-width: 800px;
  margin: 0 auto;
  background: var(--card-bg);
  border: 1px solid var(--glass-border);
  border-radius: 20px;
  box-shadow: var(--glass-shadow);
  overflow: hidden;
  text-align: left;
}

.visual-card-header {
  background: var(--bg-alt);
  padding: 14px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--border-color);
}

.window-dots {
  display: flex;
  gap: 8px;
}

.window-dots .dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
}

.window-dots .red { background-color: #ff5f56; }
.window-dots .yellow { background-color: #ffbd2e; }
.window-dots .green { background-color: #27c93f; }

.window-title {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.thinking-badge-active {
  background: rgba(139, 92, 246, 0.15);
  color: var(--accent-purple);
  font-size: 0.78rem;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.visual-card-body {
  padding: 24px;

}

.mock-accordion {
  background: rgba(139, 92, 246, 0.06);
  border: 1px solid rgba(139, 92, 246, 0.2);
  border-radius: 12px;
  margin-bottom: 16px;
  overflow: hidden;
}

.mock-accordion-header {
  padding: 12px 16px;
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  font-size: 0.92rem;
  color: var(--accent-purple);

}

.glow-icon {
  animation: pulse-glow 2s infinite ease-in-out;
}

@keyframes pulse-glow {
  0%, 100% { opacity: 0.6; transform: scale(1); }
  50% { opacity: 1; transform: scale(1.15); }
}

.mock-tag {
  margin-left: auto;
  font-size: 0.72rem;
  background: var(--accent-purple);
  color: #fff;
  padding: 2px 8px;
  border-radius: 10px;
}

.mock-accordion-content {
  padding: 0 16px 14px;
  font-size: 0.88rem;
  color: var(--text-secondary);
  border-top: 1px dashed rgba(139, 92, 246, 0.2);

}

.mock-step {
  margin-top: 8px;
}

.mock-response-box {
  background: var(--bg-alt);
  padding: 16px;
  border-radius: 12px;
  font-size: 0.95rem;
  line-height: 1.6;
}

.mock-response-box code {
  font-family: var(--font-mono);
  background: rgba(139, 92, 246, 0.15);
  color: var(--accent-purple);
  padding: 2px 6px;
  border-radius: 6px;
}

/* Sections Layout */
.intro-section {
  padding: 100px 24px;
}

.intro-section.alt-bg {
  background-color: var(--bg-alt);
}

.section-container {
  max-width: 1200px;
  margin: 0 auto;
}

.section-header {
  text-align: center;
  max-width: 720px;
  margin: 0 auto 60px;
}

.section-badge {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--accent-purple);
  letter-spacing: 1.5px;
  text-transform: uppercase;
  margin-bottom: 8px;
  display: block;
}

.section-title {
  font-size: 2.3rem;
  font-weight: 800;
  letter-spacing: -0.5px;
  margin-bottom: 14px;
}

.section-desc {
  font-size: 1.08rem;
  color: var(--text-secondary);
}

/* Features Grid */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 28px;
}

.feature-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 20px;
  padding: 32px;
  transition: all 0.3s ease;
}

.feature-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--card-hover-shadow);
  border-color: rgba(139, 92, 246, 0.4);
}

.feature-icon {
  width: 56px;
  height: 56px;
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 20px;
}

.icon-purple { background: rgba(139, 92, 246, 0.15); color: var(--accent-purple); }
.icon-blue { background: rgba(59, 130, 246, 0.15); color: var(--accent-blue); }
.icon-green { background: rgba(16, 185, 129, 0.15); color: var(--accent-green); }
.icon-orange { background: rgba(245, 158, 11, 0.15); color: var(--accent-orange); }

.feature-title {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.feature-desc {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.6;
  margin-bottom: 20px;
}

.feature-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;

}

.feature-list li {
  font-size: 0.88rem;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.feature-list li i {
  color: var(--accent-purple);
  font-size: 0.8rem;
}

/* Models Flex Layout */
.models-flex {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 24px;
}

.model-badge-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 18px;
  padding: 24px;
  transition: all 0.3s ease;
}

.model-badge-card.active {
  border-color: var(--accent-purple);
  box-shadow: 0 8px 24px rgba(139, 92, 246, 0.2);
}

.model-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 1.4rem;
  color: var(--accent-purple);
  margin-bottom: 16px;
}

.model-chip-tag {
  font-size: 0.72rem;
  font-weight: 700;
  background: var(--bg-alt);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 3px 10px;
  border-radius: 12px;
}

.model-badge-card h4 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.model-badge-card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* RAG Workflow */
.rag-workflow {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
}

.workflow-step {
  flex: 1;
  min-width: 240px;
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 20px;
  padding: 32px 24px;
  text-align: center;
}

.step-num {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--accent-purple);
  margin-bottom: 12px;
}

.step-icon {
  font-size: 2.2rem;
  color: var(--accent-purple);
  margin-bottom: 16px;
}

.workflow-step h4 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 10px;
}

.workflow-step p {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.workflow-arrow {
  font-size: 1.8rem;
  color: var(--text-muted);
}

/* FAQ Accordion */
.faq-accordion-list {
  max-width: 840px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.faq-item {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 16px;
  overflow: hidden;
  transition: border-color 0.2s ease;
}

.faq-question {
  width: 100%;
  background: none;
  border: none;
  padding: 20px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-primary);
  cursor: pointer;
  text-align: left;
}

.faq-icon {
  font-size: 0.9rem;
  color: var(--text-secondary);
  transition: transform 0.3s ease;
}

.faq-item.active .faq-icon {
  transform: rotate(180deg);
  color: var(--accent-purple);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease-out, padding 0.35s ease-out;
  padding: 0 24px;
}

.faq-item.active .faq-answer {
  max-height: 300px;
  padding: 0 24px 20px;
}

.faq-answer p {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.65;
}

/* CTA Banner Section */
.cta-banner-section {
  padding: 80px 24px;
  background: linear-gradient(135deg, rgba(139, 92, 246, 0.15), rgba(59, 130, 246, 0.15));
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
  text-align: center;
}

.banner-container {
  max-width: 800px;
  margin: 0 auto;
}

.banner-container h2 {
  font-size: 2.2rem;
  font-weight: 800;
  margin-bottom: 14px;
}

.banner-container p {
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 32px;
}

.btn-banner-primary {
  background: linear-gradient(135deg, var(--accent-purple), var(--accent-blue));
  color: #ffffff;
  text-decoration: none;
  padding: 14px 36px;
  border-radius: 14px;
  font-size: 1.1rem;
  font-weight: 700;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  box-shadow: 0 8px 24px rgba(139, 92, 246, 0.4);
  transition: all 0.3s ease;
}

.btn-banner-primary:hover {
  transform: translateY(-3px);
  box-shadow: 0 12px 30px rgba(139, 92, 246, 0.6);
}

/* Footer */
.intro-footer {
  padding: 40px 24px;
  background: var(--bg-primary);
  border-top: 1px solid var(--border-color);
}

.footer-container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  margin-bottom: 6px;
}

.footer-brand img {
  width: 28px;
  height: 28px;
}

.footer-copy {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.footer-links {
  display: flex;
  gap: 24px;
}

.footer-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.9rem;
  transition: color 0.2s ease;
}

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

/* Responsive Media Queries */
@media (max-width: 900px) {
  .nav-links {
    display: none;
  }

  .hero-headline {
    font-size: 2.3rem;
  }

  .rag-workflow {
    flex-direction: column;
  }

  .workflow-arrow {
    transform: rotate(90deg);
  }
}