/* ==========================================================================
   LINTELDESK — Premium Monochromatic Workstation Design System
   Pure Black, High-Contrast Typography, Real Hardware Software Aesthetic
   ========================================================================== */

:root {
  /* Solid Pure Black & Minimalist Dark Surfaces */
  --bg-black: #000000;
  --bg-surface-1: #0A0A0A;
  --bg-surface-2: #121212;
  --bg-surface-3: #18181B;
  --bg-surface-hover: #202024;
  
  /* Precision 1px Structural Borders */
  --border-subtle: #222222;
  --border-muted: #1A1A1A;
  --border-strong: #333333;
  --border-white: #FFFFFF;
  
  /* High-Contrast Typography */
  --text-white: #FFFFFF;
  --text-primary: #EDEDED;
  --text-secondary: #A1A1AA;
  --text-muted: #71717A;
  --text-dim: #52525B;
  
  /* Pure Monochrome Action States */
  --btn-primary-bg: #FFFFFF;
  --btn-primary-text: #000000;
  --btn-primary-hover: #E4E4E7;
  
  --btn-secondary-bg: #121212;
  --btn-secondary-text: #FFFFFF;
  --btn-secondary-border: #27272A;
  --btn-secondary-hover: #1E1E22;

  --accent-green: #22C55E;
  
  /* Typography Stack */
  --font-sans: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Inter", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: "JetBrains Mono", "SF Mono", Consolas, Menlo, monospace;
  
  /* Sizing & Structure */
  --header-height: 72px;
  --container-max: 1200px;
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  
  /* Clean Physical Elevation Shadows */
  --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.9), 0 1px 2px rgba(0, 0, 0, 0.8);
  --shadow-window: 0 20px 60px rgba(0, 0, 0, 0.95), 0 1px 0 rgba(255, 255, 255, 0.08);
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  background-color: var(--bg-black);
  color: var(--text-primary);
}

body {
  font-family: var(--font-sans);
  line-height: 1.6;
  background-color: var(--bg-black);
  color: var(--text-primary);
  overflow-x: hidden;
}

/* Typography */
h1, h2, h3, h4 {
  color: var(--text-white);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.03em;
}

p {
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

p:last-child {
  margin-bottom: 0;
}

a {
  color: var(--text-white);
  text-decoration: none;
  transition: opacity 0.15s ease;
}

a:hover {
  opacity: 0.8;
}

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

code, .mono {
  font-family: var(--font-mono);
}

/* Container & Sections */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 1.5rem;
}

.section {
  padding: 6rem 0;
}

.section-divider {
  height: 1px;
  background: var(--border-muted);
  width: 100%;
}

.section-head {
  text-align: center;
  max-width: 720px;
  margin: 0 auto 3.5rem auto;
}

.section-head h2 {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 0.75rem;
}

.section-head p {
  font-size: 1.125rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.875rem 1.625rem;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.9375rem;
  line-height: 1;
  transition: all 0.15s ease;
  white-space: nowrap;
}

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

.btn-primary:hover {
  background-color: var(--btn-primary-hover);
  color: #000000;
  transform: translateY(-1px);
}

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

.btn-secondary:hover {
  background-color: var(--btn-secondary-hover);
  border-color: var(--border-strong);
  color: #FFFFFF;
}

.btn-lg {
  padding: 1rem 2rem;
  font-size: 1rem;
}

.btn-sm {
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
}

/* Header Navigation */
.header {
  position: sticky;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--header-height);
  background-color: rgba(0, 0, 0, 0.92);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-muted);
  z-index: 100;
}

.nav-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.brand-link {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
}

.brand-logo-img {
  height: 38px;
  width: auto;
  display: block;
  object-fit: contain;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 2.25rem;
  list-style: none;
}

.nav-link {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color 0.15s ease;
}

.nav-link:hover {
  color: var(--text-white);
}

.mobile-toggle {
  display: none;
  color: var(--text-white);
  padding: 0.4rem;
}

/* Hero Section */
.hero {
  padding: 5.5rem 0 6.5rem 0;
  background-color: var(--bg-black);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.05fr 1.25fr;
  gap: 4rem;
  align-items: center;
}

.hero-content h1 {
  font-size: 3.75rem;
  font-weight: 800;
  line-height: 1.08;
  letter-spacing: -0.04em;
  margin-bottom: 1.25rem;
  color: var(--text-white);
}

.hero-content p {
  font-size: 1.1875rem;
  line-height: 1.65;
  color: var(--text-secondary);
  margin-bottom: 2.25rem;
}

.hero-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.75rem;
  flex-wrap: wrap;
}

.hero-meta {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--text-muted);
}

.hero-visual {
  position: relative;
}

.hero-frame {
  background: var(--bg-surface-1);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-window);
}

.hero-frame img {
  width: 100%;
  height: auto;
  display: block;
}

/* Features Showcase */
.features-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
}

.feature-card {
  background: var(--bg-surface-1);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-card);
  transition: border-color 0.2s ease;
}

.feature-card:hover {
  border-color: var(--border-strong);
}

.feature-card-content {
  padding: 2rem;
}

.feature-card-content h3 {
  font-size: 1.5rem;
  margin-bottom: 0.5rem;
}

.feature-card-content p {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.feature-card-media {
  background: #050505;
  border-top: 1px solid var(--border-muted);
  overflow: hidden;
}

.feature-card-media img {
  width: 100%;
  height: auto;
  display: block;
}

/* Architecture Pillars */
.pillars-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.75rem;
}

.pillar-card {
  background: var(--bg-surface-1);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 2.25rem;
}

.pillar-num {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 700;
  color: var(--text-muted);
  margin-bottom: 1rem;
  display: block;
}

.pillar-card h3 {
  font-size: 1.35rem;
  margin-bottom: 0.625rem;
}

.pillar-card p {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* Comparison Table */
.comp-card {
  background: var(--bg-surface-1);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.comp-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}

.comp-table th, .comp-table td {
  padding: 1.25rem 1.75rem;
  border-bottom: 1px solid var(--border-muted);
}

.comp-table th {
  background: var(--bg-surface-2);
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

.comp-table th.highlight-col, .comp-table td.highlight-col {
  background: #0E0E10;
  color: var(--text-white);
  font-weight: 600;
}

.comp-table td.highlight-col {
  color: var(--accent-green);
}

/* Pricing Card */
.pricing-wrapper {
  max-width: 640px;
  margin: 0 auto;
}

.pricing-card {
  background: var(--bg-surface-1);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-xl);
  padding: 3.5rem 3rem;
  text-align: center;
  box-shadow: var(--shadow-card);
}

.pricing-plan-title {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

.pricing-price-row {
  display: flex;
  align-items: baseline;
  justify-content: center;
  gap: 0.35rem;
  margin: 1.25rem 0 0.5rem 0;
}

.pricing-currency {
  font-size: 2.25rem;
  font-weight: 700;
  color: var(--text-muted);
}

.pricing-number {
  font-size: 4.5rem;
  font-weight: 900;
  letter-spacing: -0.05em;
  color: var(--text-white);
  line-height: 1;
}

.pricing-term {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: var(--accent-green);
  font-weight: 600;
}

.pricing-desc {
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 2rem;
}

.pricing-features-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.875rem;
  text-align: left;
  max-width: 440px;
  margin: 0 auto 2.5rem auto;
  padding: 1.5rem;
  background: var(--bg-surface-2);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
}

.pricing-feature-line {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.9375rem;
  color: var(--text-primary);
}

.pricing-feature-line svg {
  color: var(--accent-green);
  flex-shrink: 0;
}

.payment-badges-row {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 1.25rem;
}

/* Download Section */
.download-card {
  background: var(--bg-surface-1);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
  padding: 3rem;
  display: flex;
  flex-direction: column;
  gap: 1.75rem;
}

.download-actions-row {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  flex-wrap: wrap;
}

.checksum-pill {
  background: #050505;
  border: 1px solid var(--border-muted);
  border-radius: var(--radius-sm);
  padding: 0.75rem 1rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-secondary);
  word-break: break-all;
}

/* FAQ Accordion */
.faq-container {
  max-width: 760px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.faq-item {
  background: var(--bg-surface-1);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.faq-trigger {
  width: 100%;
  padding: 1.25rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  text-align: left;
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--text-white);
}

.faq-trigger:hover {
  background: var(--bg-surface-2);
}

.faq-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.25s ease, padding 0.25s ease;
  padding: 0 1.5rem;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.faq-item.active .faq-content {
  padding: 0 1.5rem 1.25rem 1.5rem;
  max-height: 300px;
}

.faq-icon {
  transition: transform 0.2s ease;
  flex-shrink: 0;
  color: var(--text-muted);
}

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

/* Footer */
.footer {
  border-top: 1px solid var(--border-muted);
  padding: 4.5rem 0 3.5rem 0;
  background-color: var(--bg-black);
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1.75rem;
}

.footer-links-list {
  display: flex;
  gap: 2rem;
  list-style: none;
}

.footer-link {
  font-size: 0.875rem;
  color: var(--text-muted);
}

.footer-link:hover {
  color: var(--text-white);
}

.footer-copy {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--text-dim);
}

/* Responsive */
@media (max-width: 960px) {
  .hero-grid {
    grid-template-columns: 1fr;
    text-align: center;
    gap: 2.5rem;
  }
  .hero-content h1 {
    font-size: 2.75rem;
  }
  .hero-actions {
    justify-content: center;
  }
  .features-grid {
    grid-template-columns: 1fr;
  }
  .pillars-grid {
    grid-template-columns: 1fr;
  }
  .nav-menu {
    display: none;
  }
  .mobile-toggle {
    display: block;
  }
}