/* ============================================================
   Serial Terminal Landing Page - Design System & Styles
   Inspired by Anthropic's elegant editorial aesthetic
   ============================================================ */

/* --- Design Tokens --- */
:root {
  /* Colors - Light Theme (Perplexity Careers exact colors) */
  --color-bg-primary: #F4F3EA;
  --color-bg-secondary: #EEEDE4;
  --color-bg-card: #FFFFFF;
  --color-bg-card-hover: #FAFAF7;
  --color-text-primary: #0A2F34;
  --color-text-secondary: #2A5A5F;
  --color-text-muted: #5A8A8F;
  --color-accent: #20808D;
  --color-accent-hover: #186670;
  --color-accent-light: rgba(32, 128, 141, 0.08);
  --color-border: #E0DFD6;
  --color-border-light: #E9E8E0;
  --color-shadow: rgba(10, 47, 52, 0.05);
  --color-shadow-hover: rgba(10, 47, 52, 0.10);

  /* Typography */
  --font-serif: 'Playfair Display', Georgia, 'Times New Roman', serif;
  --font-sans: -apple-system, BlinkMacSystemFont, 'SF Pro Text', 'Helvetica Neue', sans-serif;
  --font-mono: 'SF Mono', 'Fira Code', 'Consolas', monospace;

  --text-hero: clamp(3.2rem, 7vw, 5.5rem);
  --text-h1: clamp(2.2rem, 4.5vw, 3.5rem);
  --text-h2: clamp(1.6rem, 3vw, 2.5rem);
  --text-h3: clamp(1.1rem, 2vw, 1.35rem);
  --text-body: 1rem;
  --text-body-lg: 1.125rem;
  --text-small: 0.875rem;
  --text-xs: 0.75rem;

  --line-height-tight: 1.2;
  --line-height-normal: 1.6;
  --line-height-relaxed: 1.8;

  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2.5rem;
  --space-xl: 4rem;
  --space-2xl: 6rem;
  --space-3xl: 8rem;

  /* Layout */
  --max-width: 1140px;
  --border-radius: 12px;
  --border-radius-lg: 20px;
  --border-radius-xl: 28px;

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);

  /* Navbar */
  --navbar-height: 64px;
}

/* --- Dark Theme --- */
[data-theme="dark"] {
  --color-bg-primary: #0A1E22;
  --color-bg-secondary: #0F2A2F;
  --color-bg-card: #143338;
  --color-bg-card-hover: #1A3D43;
  --color-text-primary: #E8F2F3;
  --color-text-secondary: #A0CDD2;
  --color-text-muted: #5A9DA5;
  --color-accent: #3DBDCA;
  --color-accent-hover: #5DD0DA;
  --color-accent-light: rgba(61, 189, 202, 0.1);
  --color-border: #1E4248;
  --color-border-light: #162F34;
  --color-shadow: rgba(0, 0, 0, 0.25);
  --color-shadow-hover: rgba(0, 0, 0, 0.4);
}

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

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

body {
  font-family: var(--font-sans);
  font-size: var(--text-body);
  line-height: var(--line-height-normal);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  transition: background-color var(--transition-normal), color var(--transition-normal);
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-accent-hover);
}

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

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

/* --- Layout --- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.section-title {
  font-family: var(--font-serif);
  font-size: var(--text-h2);
  font-weight: 600;
  color: var(--color-text-primary);
  text-align: center;
  margin-bottom: var(--space-sm);
  letter-spacing: -0.02em;
}

.section-subtitle {
  font-size: var(--text-body-lg);
  color: var(--color-text-secondary);
  text-align: center;
  max-width: 560px;
  margin: 0 auto var(--space-xl);
  line-height: var(--line-height-relaxed);
}

/* --- Navbar --- */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--navbar-height);
  display: flex;
  align-items: center;
  transition: background-color var(--transition-normal), box-shadow var(--transition-normal);
}

.navbar.scrolled {
  background: rgba(244, 243, 234, 0.88);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  box-shadow: 0 1px 0 var(--color-border-light);
}

[data-theme="dark"] .navbar.scrolled {
  background: rgba(10, 30, 34, 0.88);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  font-family: var(--font-serif);
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--color-text-primary);
  text-decoration: none;
}

.nav-logo-icon {
  width: 28px;
  height: 28px;
  border-radius: 8px;
  flex: 0 0 auto;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.nav-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 8px 12px;
  border-radius: 8px;
  color: var(--color-text-secondary);
  font-size: var(--text-small);
  font-weight: 500;
  transition: all var(--transition-fast);
}

.nav-btn:hover {
  background: var(--color-accent-light);
  color: var(--color-accent);
}

#theme-toggle {
  padding: 8px;
}

.icon-moon { display: none; }
[data-theme="dark"] .icon-sun { display: none; }
[data-theme="dark"] .icon-moon { display: block; }

/* --- Hero Section --- */
.hero {
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: calc(var(--navbar-height) + var(--space-xl)) var(--space-lg) var(--space-3xl);
}

.hero-title {
  font-family: var(--font-serif);
  font-size: var(--text-hero);
  font-weight: 700;
  color: var(--color-text-primary);
  letter-spacing: -0.03em;
  line-height: var(--line-height-tight);
  margin-bottom: var(--space-md);
}

.hero-subtitle {
  font-size: clamp(1.1rem, 2.5vw, 1.4rem);
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto var(--space-sm);
  line-height: var(--line-height-relaxed);
}

.hero-desc {
  font-size: var(--text-body);
  color: var(--color-text-muted);
  max-width: 500px;
  margin: 0 auto var(--space-lg);
  line-height: var(--line-height-relaxed);
}

.hero-cta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  margin-bottom: var(--space-lg);
  flex-wrap: wrap;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  padding: 6px 16px;
  border-radius: 100px;
  background: var(--color-accent-light);
  border: 1px solid var(--color-border-light);
}

.hero-badge span {
  font-size: var(--text-small);
  color: var(--color-text-muted);
  font-weight: 500;
}

/* Hero Visual */
.hero-visual {
  margin-top: var(--space-xl);
  width: 100%;
  max-width: 900px;
  margin-left: auto;
  margin-right: auto;
}

.hero-screenshot-frame {
  border-radius: var(--border-radius-lg);
  overflow: hidden;
  box-shadow:
    0 24px 64px var(--color-shadow-hover),
    0 0 0 1px var(--color-border-light);
}

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

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 14px 32px;
  border-radius: 100px;
  font-size: var(--text-body);
  font-weight: 500;
  text-decoration: none;
  transition: all var(--transition-normal);
  cursor: pointer;
}

.btn-icon {
  width: 18px;
  height: 18px;
  flex: 0 0 auto;
}

.btn-lg .btn-icon {
  width: 20px;
  height: 20px;
}

.btn-primary {
  background: var(--color-accent);
  color: #FFFFFF;
}

.btn-primary:hover {
  background: var(--color-accent-hover);
  color: #FFFFFF;
  transform: translateY(-2px);
  box-shadow: 0 8px 24px var(--color-shadow-hover);
}

.btn-secondary {
  background: transparent;
  color: var(--color-text-primary);
  border: 1.5px solid var(--color-border);
}

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

.btn-lg {
  padding: 18px 40px;
  font-size: var(--text-body-lg);
  border-radius: 100px;
}

/* --- Features Section --- */
.features {
  padding: var(--space-3xl) 0;
  background: var(--color-bg-secondary);
}

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

.feature-card {
  padding: var(--space-lg);
  border-radius: var(--border-radius);
  background: var(--color-bg-card);
  border: 1px solid var(--color-border-light);
  transition: all var(--transition-normal);
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 16px 48px var(--color-shadow-hover);
  border-color: var(--color-accent);
}

.feature-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 52px;
  height: 52px;
  border-radius: 12px;
  background: var(--color-accent-light);
  color: var(--color-accent);
  margin-bottom: var(--space-md);
}

.feature-card h3 {
  font-family: var(--font-serif);
  font-size: var(--text-h3);
  font-weight: 600;
  color: var(--color-text-primary);
  margin-bottom: var(--space-xs);
}

.feature-card p {
  font-size: var(--text-small);
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
}

/* --- Screenshots Section --- */
.screenshots {
  padding: var(--space-3xl) 0;
  background: var(--color-bg-secondary);
}

.screenshots-showcase {
  max-width: 900px;
  margin: 0 auto;
}

.screenshot-tabs {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xs);
  margin-bottom: var(--space-lg);
  flex-wrap: wrap;
}

.screenshot-tabs .tab {
  padding: 10px 20px;
  border-radius: 100px;
  font-size: var(--text-small);
  font-weight: 500;
  color: var(--color-text-muted);
  border: 1px solid transparent;
  transition: all var(--transition-fast);
}

.screenshot-tabs .tab:hover {
  color: var(--color-text-primary);
  background: var(--color-accent-light);
}

.screenshot-tabs .tab.active {
  color: var(--color-accent);
  background: var(--color-accent-light);
  border-color: var(--color-accent);
}

.screenshot-display {
  position: relative;
  border-radius: var(--border-radius-lg);
  overflow: hidden;
  box-shadow: 0 24px 64px var(--color-shadow-hover);
  background: var(--color-bg-card);
  border: 1px solid var(--color-border-light);
  aspect-ratio: 101/70;
  margin-bottom: var(--space-md);
}

.screenshot-img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: contain;
  opacity: 0;
  transition: opacity 0.4s ease;
  padding: 0;
}

.screenshot-img.active {
  opacity: 1;
}

.screenshot-descs {
  text-align: center;
  min-height: 2.5em;
}

.screenshot-desc {
  display: none;
  font-size: var(--text-body);
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
}

.screenshot-desc.active {
  display: block;
}

/* --- Video Demo Section --- */
.demo {
  padding: var(--space-3xl) 0;
}

.video-wrapper {
  max-width: 860px;
  margin: 0 auto;
  border-radius: var(--border-radius-lg);
  overflow: hidden;
  box-shadow: 0 24px 64px var(--color-shadow-hover);
  background: #000;
}

.video-wrapper video {
  width: 100%;
  display: block;
}

.video-poster {
  position: relative;
  cursor: pointer;
}

.video-poster img {
  width: 100%;
  height: auto;
  display: block;
}

.play-btn {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: #FFFFFF;
  filter: drop-shadow(0 4px 12px rgba(0, 0, 0, 0.3));
  transition: transform var(--transition-normal), opacity var(--transition-fast);
}

.play-btn:hover {
  transform: translate(-50%, -50%) scale(1.1);
  opacity: 0.9;
}

/* --- Privacy Section --- */
.privacy {
  padding: var(--space-3xl) 0;
}

.privacy-card {
  max-width: 600px;
  margin: 0 auto;
  text-align: center;
  padding: var(--space-xl) var(--space-lg);
  background: var(--color-bg-card);
  border-radius: var(--border-radius-xl);
  border: 1px solid var(--color-border-light);
  box-shadow: 0 8px 32px var(--color-shadow);
}

.privacy-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-md);
  color: var(--color-accent);
}

.privacy-card h2 {
  font-family: var(--font-serif);
  font-size: var(--text-h2);
  font-weight: 600;
  color: var(--color-text-primary);
  margin-bottom: var(--space-xs);
}

.privacy-subtitle {
  font-size: var(--text-body-lg);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-lg);
}

.privacy-list {
  list-style: none;
  padding: 0;
  text-align: left;
  max-width: 320px;
  margin: 0 auto;
}

.privacy-list li {
  padding: var(--space-xs) 0;
  font-size: var(--text-body);
  color: var(--color-text-secondary);
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.privacy-list li::before {
  content: '';
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--color-accent-light);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%2320808D' stroke-width='3' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M20 6L9 17l-5-5'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: center;
}

[data-theme="dark"] .privacy-list li::before {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%233DBDCA' stroke-width='3' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M20 6L9 17l-5-5'/%3E%3C/svg%3E");
}

/* --- CTA Section (dark teal block like Perplexity "Join Us") --- */
.cta-section {
  padding: var(--space-3xl) 0;
  text-align: center;
  background: #105058;
}

.cta-title {
  font-family: var(--font-serif);
  font-size: var(--text-h1);
  font-weight: 600;
  color: #FFFFFF;
  margin-bottom: var(--space-sm);
  letter-spacing: -0.02em;
}

.cta-desc {
  font-size: var(--text-body-lg);
  color: rgba(255, 255, 255, 0.7);
  margin-bottom: var(--space-lg);
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
}

.cta-section .btn-primary {
  background: var(--color-accent);
  color: #FFFFFF;
  padding: 18px 40px;
  border-radius: 100px;
}

.cta-section .btn-primary:hover {
  background: var(--color-accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.3);
}

/* --- Footer --- */
.footer {
  padding: var(--space-xl) 0;
  border-top: 1px solid var(--color-border-light);
}

.footer-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.footer-logo {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-text-primary);
  margin-bottom: 4px;
}

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

.footer-links {
  display: flex;
  gap: var(--space-md);
}

.footer-links a {
  font-size: var(--text-small);
  color: var(--color-text-muted);
  transition: color var(--transition-fast);
}

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

/* --- Scroll Animations --- */
[data-animate] {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.7s cubic-bezier(0.4, 0, 0.2, 1), transform 0.7s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-animate].animate-in {
  opacity: 1;
  transform: translateY(0);
}

/* Stagger animation for feature cards */
.feature-card:nth-child(1) { transition-delay: 0s; }
.feature-card:nth-child(2) { transition-delay: 0.08s; }
.feature-card:nth-child(3) { transition-delay: 0.16s; }
.feature-card:nth-child(4) { transition-delay: 0.24s; }
.feature-card:nth-child(5) { transition-delay: 0.32s; }
.feature-card:nth-child(6) { transition-delay: 0.40s; }
.feature-card:nth-child(7) { transition-delay: 0.48s; }

/* --- Responsive --- */
@media (max-width: 768px) {
  .container {
    padding: 0 var(--space-md);
  }

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

  .hero {
    padding-top: calc(var(--navbar-height) + var(--space-lg));
  }

  .hero-screenshot-frame {
    border-radius: var(--border-radius);
  }

  .screenshot-tabs {
    gap: 4px;
  }

  .screenshot-tabs .tab {
    padding: 8px 14px;
    font-size: var(--text-xs);
  }

  .screenshot-display {
    border-radius: var(--border-radius);
  }

  .privacy-card {
    padding: var(--space-lg) var(--space-md);
  }

  .footer-content {
    flex-direction: column;
    text-align: center;
  }

  .video-wrapper {
    border-radius: var(--border-radius);
  }

  .section-title {
    margin-bottom: var(--space-xs);
  }

  .section-subtitle {
    margin-bottom: var(--space-lg);
  }
}

@media (max-width: 480px) {
  .hero-cta {
    flex-direction: column;
    width: 100%;
  }

  .hero-cta .btn {
    width: 100%;
  }

  .nav-logo span {
    font-size: 1rem;
  }

  .features-grid {
    gap: var(--space-sm);
  }

  .feature-card {
    padding: var(--space-md);
  }
}

/* --- Print --- */
@media print {
  .navbar,
  .nav-actions,
  .hero-cta,
  .cta-section {
    display: none;
  }

  body {
    background: white;
    color: black;
  }
}