/* ===== CSS Variables ===== */
:root {
  --bg-primary: #0a0e17;
  --bg-secondary: #111827;
  --bg-card: #1a2236;
  --bg-card-hover: #1f2a42;
  --bg-glass: rgba(26, 34, 54, 0.7);
  --bg-modal-overlay: rgba(0, 0, 0, 0.75);
  --accent: #3b82f6;
  --accent-hover: #60a5fa;
  --accent-glow: rgba(59, 130, 246, 0.25);
  --accent-subtle: rgba(59, 130, 246, 0.1);
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --border: rgba(148, 163, 184, 0.1);
  --border-accent: rgba(59, 130, 246, 0.3);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.4);
  --shadow-glow: 0 0 20px var(--accent-glow);
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

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

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

/* ===== Top Navigation Bar ===== */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 14, 23, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  padding: 0 2rem;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.navbar-brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-weight: 700;
  font-size: 1.1rem;
  letter-spacing: -0.02em;
}

.navbar-brand .logo-icon {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, var(--accent), #8b5cf6);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.85rem;
}

.navbar-links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.navbar-links a {
  padding: 0.5rem 1rem;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: var(--transition);
}

.navbar-links a:hover,
.navbar-links a.active {
  color: var(--text-primary);
  background: var(--accent-subtle);
}

.navbar-links a.active {
  color: var(--accent);
}

/* ===== Hero Section (Landing) ===== */
.hero {
  min-height: calc(100vh - 64px);
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 4rem 2rem;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -40%;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 800px;
  background: radial-gradient(circle, var(--accent-glow), transparent 70%);
  pointer-events: none;
  opacity: 0.5;
}

.hero-content {
  position: relative;
  max-width: 720px;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 1rem;
  border-radius: 9999px;
  border: 1px solid var(--border-accent);
  background: var(--accent-subtle);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent);
  margin-bottom: 2rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.hero h1 {
  font-size: clamp(2.5rem, 6vw, 4rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: 1.5rem;
  background: linear-gradient(135deg, var(--text-primary), var(--text-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero h1 span {
  background: linear-gradient(135deg, var(--accent), #8b5cf6);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 540px;
  margin: 0 auto 2.5rem;
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.75rem;
  border-radius: var(--radius-md);
  font-size: 0.95rem;
  font-weight: 600;
  transition: var(--transition);
  white-space: nowrap;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  box-shadow: var(--shadow-glow);
}

.btn-primary:hover {
  background: var(--accent-hover);
  box-shadow: 0 0 30px var(--accent-glow);
  transform: translateY(-2px);
}

.btn-secondary {
  background: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-accent);
  transform: translateY(-2px);
}

.btn-ghost {
  color: var(--text-secondary);
  padding: 0.5rem 1rem;
}

.btn-ghost:hover {
  color: var(--text-primary);
  background: var(--accent-subtle);
}

.btn-icon {
  width: 40px;
  height: 40px;
  padding: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  border: 1px solid var(--border);
  transition: var(--transition);
}

.btn-icon:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-accent);
}

/* ===== Features Grid (Landing) ===== */
.features {
  padding: 4rem 2rem 6rem;
  max-width: 1100px;
  margin: 0 auto;
}

.features-title {
  text-align: center;
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  letter-spacing: -0.02em;
}

.features-subtitle {
  text-align: center;
  color: var(--text-secondary);
  margin-bottom: 3rem;
  font-size: 0.95rem;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.25rem;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  transition: var(--transition);
}

.feature-card:hover {
  border-color: var(--border-accent);
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.feature-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  background: var(--accent-subtle);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  margin-bottom: 1rem;
}

.feature-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.feature-card p {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ===== Steps Page Layout ===== */
.steps-layout {
  display: grid;
  grid-template-columns: 380px 1fr;
  min-height: calc(100vh - 64px);
}

.steps-sidebar {
  background: var(--bg-secondary);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.sidebar-header {
  padding: 1.5rem;
  border-bottom: 1px solid var(--border);
}

.sidebar-header h2 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
}

.search-box {
  position: relative;
}

.search-box input {
  width: 100%;
  padding: 0.6rem 1rem 0.6rem 2.5rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--text-primary);
  font-size: 0.875rem;
  font-family: inherit;
  transition: var(--transition);
  outline: none;
}

.search-box input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.search-box input::placeholder {
  color: var(--text-muted);
}

.search-box .search-icon {
  position: absolute;
  left: 0.75rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  font-size: 0.85rem;
  pointer-events: none;
}

.steps-list {
  flex: 1;
  overflow-y: auto;
  padding: 0.75rem;
}

.steps-list::-webkit-scrollbar {
  width: 6px;
}

.steps-list::-webkit-scrollbar-track {
  background: transparent;
}

.steps-list::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 3px;
}

.step-item {
  display: flex;
  align-items: center;
  gap: 0.875rem;
  padding: 0.875rem 1rem;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: var(--transition);
  margin-bottom: 0.25rem;
  border: 1px solid transparent;
}

.step-item:hover {
  background: var(--bg-card);
  border-color: var(--border);
}

.step-item.active {
  background: var(--accent-subtle);
  border-color: var(--border-accent);
}

.step-number {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--bg-card);
  border: 2px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: 700;
  flex-shrink: 0;
  transition: var(--transition);
}

.step-item.active .step-number {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
  box-shadow: var(--shadow-glow);
}

.step-item:hover .step-number {
  border-color: var(--accent);
}

.step-info {
  flex: 1;
  min-width: 0;
}

.step-title {
  font-size: 0.9rem;
  font-weight: 600;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.step-desc {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.15rem;
}

.step-item.active .step-title {
  color: var(--accent);
}

.step-arrow {
  color: var(--text-muted);
  font-size: 0.85rem;
  opacity: 0;
  transition: var(--transition);
}

.step-item:hover .step-arrow,
.step-item.active .step-arrow {
  opacity: 1;
}

/* ===== Viewer Panel ===== */
.viewer-panel {
  display: flex;
  flex-direction: column;
  background: var(--bg-primary);
}

.viewer-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
  background: var(--bg-secondary);
  min-height: 60px;
}

.viewer-toolbar-left {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.viewer-toolbar-title {
  font-size: 0.95rem;
  font-weight: 600;
}

.viewer-toolbar-step {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.viewer-toolbar-right {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.viewer-content {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}

.viewer-content iframe,
.viewer-content embed {
  width: 100%;
  height: 100%;
  border: none;
}

/* ===== Empty State ===== */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 3rem;
  height: 100%;
}

.empty-state-icon {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  background: var(--bg-card);
  border: 2px dashed var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  margin-bottom: 1.5rem;
  color: var(--text-muted);
}

.empty-state h3 {
  font-size: 1.2rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.empty-state p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  max-width: 320px;
}

/* ===== Loading State ===== */
.loading-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-primary);
  z-index: 5;
  transition: opacity 0.3s;
}

.loading-overlay.hidden {
  opacity: 0;
  pointer-events: none;
}

.spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

/* ===== PDF Viewer Standalone Page ===== */
.viewer-page {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.viewer-page .viewer-content {
  flex: 1;
}

.viewer-page iframe {
  width: 100%;
  height: 100%;
  border: none;
}

/* ===== Navigation Buttons (Prev/Next) ===== */
.nav-buttons {
  display: flex;
  gap: 0.5rem;
}

.nav-btn {
  padding: 0.4rem 0.85rem;
  font-size: 0.8rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.nav-btn:hover:not(:disabled) {
  background: var(--bg-card-hover);
  border-color: var(--border-accent);
  color: var(--text-primary);
}

.nav-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

/* ===== Footer ===== */
.footer {
  padding: 2rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.8rem;
  border-top: 1px solid var(--border);
}

/* ===== Animations ===== */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.animate-in {
  animation: fadeInUp 0.5s ease forwards;
  opacity: 0;
}

/* ===== Responsive ===== */
@media (max-width: 1024px) {
  .steps-layout {
    grid-template-columns: 1fr;
    grid-template-rows: auto 1fr;
  }

  .steps-sidebar {
    max-height: 45vh;
    border-right: none;
    border-bottom: 1px solid var(--border);
  }

  .viewer-panel {
    min-height: 55vh;
  }
}

@media (max-width: 768px) {
  .navbar {
    padding: 0 1rem;
  }

  .hero {
    padding: 3rem 1.5rem;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .hero p {
    font-size: 1rem;
  }

  .features {
    padding: 3rem 1.5rem;
  }

  .features-grid {
    grid-template-columns: 1fr;
  }

  .steps-sidebar {
    max-height: 40vh;
  }

  .viewer-toolbar {
    flex-wrap: wrap;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
  }

  .step-item {
    padding: 0.75rem;
  }
}

@media (max-width: 480px) {
  .hero-actions {
    flex-direction: column;
    align-items: center;
  }

  .btn {
    width: 100%;
    justify-content: center;
  }

  .navbar-links a {
    padding: 0.5rem 0.6rem;
    font-size: 0.8rem;
  }
}