/* Download Toast */
.download-toast {
  position: fixed;
  top: 24px;
  right: 24px;
  background: #ffffff;
  color: #0a0a0a;
  padding: 12px 20px;
  border-radius: 8px;
  font-size: 0.875rem;
  font-weight: 600;
  box-shadow: 0 4px 20px rgba(0,0,0,0.3);
  opacity: 0;
  transform: translateY(-8px);
  transition: opacity 0.3s ease, transform 0.3s ease;
  pointer-events: none;
  z-index: 9999;
}
.download-toast.show {
  opacity: 1;
  transform: translateY(0);
}

/* Chrome download warning notice */
.download-warning {
  margin-top: var(--space-md);
  padding: 12px 16px;
  background: rgba(99, 179, 237, 0.08);
  border: 1px solid rgba(99, 179, 237, 0.25);
  border-radius: 8px;
  color: #63b3ed;
  font-size: 0.875rem;
  line-height: 1.5;
  max-width: 560px;
  margin-left: auto;
  margin-right: auto;
  text-align: center;
}

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

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

/* Design Tokens */
:root {
  /* Backgrounds */
  --bg-primary: #0a0a0a;
  --bg-secondary: #111111;
  --bg-card: #1a1a1a;
  --bg-card-hover: #222222;
  --bg-surface: #1e1e1e;

  /* Text */
  --text-primary: #f0f0f0;
  --text-secondary: #8a8a9a;
  --text-on-accent: #0a0a0a;

  /* Accent */
  --accent-white: #ffffff;
  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-card: rgba(255, 255, 255, 0.06);

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

  /* Layout */
  --max-width: 1200px;
  --header-height: 72px;
  --border-radius-sm: 8px;
  --border-radius-md: 12px;
  --border-radius-lg: 24px;
  --border-radius-pill: 999px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
}

/* Global Styles */
html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

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

input,
textarea {
  font: inherit;
}

/* Main content area */
.main {
  padding-top: var(--header-height);
}

/* ===== HEADER ===== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  z-index: 100;
  background-color: rgba(10, 10, 10, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-subtle);
}

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

.logo {
  display: flex;
  align-items: center;
  white-space: nowrap;
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--text-primary);
}

.logo-img {
  height: 20px;
  width: auto;
  margin-right: 8px;
}

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

.nav-link {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

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

.header-actions {
  display: flex;
  align-items: center;
}

.download-hint {
  font-size: 0.875rem;
  font-weight: 500;
  color: #ffffff;
}

.mobile-download {
  display: none;
}

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 24px;
  height: 24px;
  padding: 0;
}

.hamburger span {
  display: block;
  width: 100%;
  height: 2px;
  background-color: var(--text-primary);
  border-radius: 1px;
  transition: all var(--transition-fast);
}

.hamburger.open span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.hamburger.open span:nth-child(2) {
  opacity: 0;
}

.hamburger.open span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ===== FOOTER ===== */
.footer {
  border-top: 1px solid var(--border-subtle);
  background-color: var(--bg-secondary);
  padding: var(--space-3xl) 0 var(--space-xl);
}

.footer-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  text-align: center;
}

.footer-top {
  margin-bottom: var(--space-lg);
}

.footer-brand {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--text-primary);
}

.footer-tagline {
  margin-top: var(--space-xs);
  font-size: 0.9375rem;
  color: var(--text-secondary);
}

.footer-links {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: var(--space-md);
  margin-bottom: var(--space-lg);
}

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

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

.footer-bottom {
  font-size: 0.8125rem;
  color: var(--text-secondary);
}

/* ===== BUTTONS ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  border-radius: var(--border-radius-pill);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.btn-primary {
  background-color: var(--accent-white);
  color: var(--text-on-accent);
}

.btn-primary:hover {
  opacity: 0.9;
  transform: scale(1.02);
}

.btn-secondary {
  background-color: transparent;
  color: var(--text-primary);
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.btn-secondary:hover {
  border-color: rgba(255, 255, 255, 0.4);
  background-color: rgba(255, 255, 255, 0.05);
}

.btn-sm {
  padding: 0.375rem 1rem;
  font-size: 0.8125rem;
}

.btn-md {
  padding: 0.5rem 1.25rem;
  font-size: 0.875rem;
}

.btn-lg {
  padding: 0.75rem 1.75rem;
  font-size: 1rem;
}

/* ===== SECTION HEADING ===== */
.section-heading {
  margin-bottom: var(--space-xl);
  text-align: center;
}

.section-heading h2 {
  font-size: clamp(1.75rem, 3vw, 2.5rem);
  font-weight: 700;
  line-height: 1.2;
  color: var(--text-primary);
}

.section-heading .subtitle {
  margin-top: var(--space-sm);
  font-size: 1.0625rem;
  line-height: 1.6;
  color: var(--text-secondary);
  max-width: 640px;
  margin-left: auto;
  margin-right: auto;
}

/* ===== FEATURE CARD ===== */
.feature-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--border-radius-md);
  padding: var(--space-lg);
  transition: all var(--transition-normal);
}

.feature-card:hover {
  background-color: var(--bg-card-hover);
  border-color: var(--border-subtle);
}

.feature-card h3 {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-xs);
  line-height: 1.3;
}

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

/* ===== ARTICLE CARD ===== */
.article-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--border-radius-sm);
  padding: var(--space-sm) var(--space-md);
  transition: all var(--transition-fast);
}

.article-card:hover {
  background-color: var(--bg-card-hover);
  border-color: var(--border-subtle);
}

.article-card-label {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-primary);
}

.article-card-arrow {
  font-size: 1.125rem;
  color: var(--text-secondary);
  transition: transform var(--transition-fast);
}

.article-card:hover .article-card-arrow {
  transform: translateX(4px);
  color: var(--text-primary);
}

/* ===== LANDING PAGE ===== */

/* Hero */
.hero {
  min-height: 85vh;
  display: flex;
  align-items: center;
  background: linear-gradient(180deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
}

.hero-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  width: 100%;
  display: flex;
  align-items: center;
  gap: var(--space-xl);
}

.hero-content {
  flex: 1;
  max-width: 720px;
}

/* Ad Slots */
.ad-slot {
  background: #c8c8c8;
  border-radius: 4px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #888;
  font-size: 0.85rem;
  font-weight: 400;
  flex-shrink: 0;
}

.ad-slot-leaderboard {
  width: 100%;
  height: 90px;
  margin: var(--space-lg) auto;
}

.ad-slot-rectangle {
  width: 300px;
  height: 250px;
}

.hero-title {
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: 800;
  line-height: 1.1;
  color: var(--text-primary);
}

.hero-title-accent {
  color: var(--text-secondary);
}

.hero-tagline {
  margin-top: var(--space-md);
  font-size: clamp(1.125rem, 2vw, 1.375rem);
  color: var(--text-secondary);
  line-height: 1.5;
}

.hero-download-hint {
  margin-top: var(--space-xl);
  font-size: 1rem;
  color: #ffffff;
}

/* Sections */
.section {
  padding: var(--space-3xl) 0;
}

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

/* Prose */
.prose-with-ads {
  display: flex;
  align-items: flex-start;
  gap: var(--space-xl);
}

.prose-with-ads .prose {
  flex: 1;
  max-width: none;
  margin: 0;
  text-align: left;
}

.prose-ads {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  flex-shrink: 0;
}

.prose {
  max-width: 520px;
  margin: 0 auto;
  text-align: center;
}

.prose p {
  font-size: 1.0625rem;
  line-height: 1.7;
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
}

.prose-download-hint {
  margin-top: var(--space-lg);
  font-size: 0.9375rem;
  color: #ffffff;
}

/* Features grid */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: var(--space-md);
}

/* Guide */
.guide-intro {
  text-align: center;
  font-size: 1.0625rem;
  line-height: 1.7;
  color: var(--text-secondary);
  max-width: 720px;
  margin: 0 auto var(--space-2xl);
}

.guide-part {
  margin-bottom: var(--space-2xl);
}

.guide-part:last-child {
  margin-bottom: 0;
}

.guide-part-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-xs);
}

.guide-part-description {
  font-size: 0.9375rem;
  line-height: 1.6;
  color: var(--text-secondary);
  margin-bottom: var(--space-md);
  max-width: 640px;
}

.guide-articles {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

/* Download section */
.download-section {
  padding: var(--space-3xl) 0;
  background-color: var(--bg-secondary);
  text-align: center;
  border-top: 1px solid var(--border-subtle);
}

.download-text {
  font-size: 1.0625rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-lg);
}

.download-cta {
  margin-bottom: var(--space-md);
}

.download-meta {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
}

.download-note {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
  max-width: 560px;
  margin: 0 auto var(--space-sm);
}

.download-help {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.inline-link {
  color: var(--text-primary);
  text-decoration: underline;
  text-decoration-color: rgba(255, 255, 255, 0.3);
  text-underline-offset: 3px;
  transition: text-decoration-color var(--transition-fast);
}

.inline-link:hover {
  text-decoration-color: var(--text-primary);
}

/* ===== CONTENT PAGES (sub-pages) ===== */
.content-page {
  min-height: 60vh;
}

.content-hero {
  padding: var(--space-3xl) 0 var(--space-2xl);
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border-subtle);
}

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

.content-title {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 700;
  line-height: 1.2;
  color: var(--text-primary);
}

.content-subtitle {
  margin-top: var(--space-sm);
  font-size: 1.0625rem;
  line-height: 1.6;
  color: var(--text-secondary);
}

.content-body {
  padding: var(--space-2xl) 0 var(--space-3xl);
}

.content-body h2 {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-top: var(--space-2xl);
  margin-bottom: var(--space-sm);
}

.content-body h2:first-child {
  margin-top: 0;
}

.content-body h3 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-top: var(--space-xl);
  margin-bottom: var(--space-xs);
}

.content-body p {
  font-size: 1rem;
  line-height: 1.7;
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
}

.content-body ul,
.content-body ol {
  margin-bottom: var(--space-sm);
  padding-left: var(--space-md);
  color: var(--text-secondary);
  line-height: 1.7;
}

.content-body li {
  margin-bottom: var(--space-xs);
}

.content-body a {
  color: var(--text-primary);
  text-decoration: underline;
  text-decoration-color: rgba(255, 255, 255, 0.3);
  text-underline-offset: 3px;
}

.content-body a:hover {
  text-decoration-color: var(--text-primary);
}

/* ===== CONTACT FORM ===== */
.contact-form {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  max-width: 560px;
}

.form-field {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.form-label {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-primary);
}

.form-input,
.form-textarea {
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--border-radius-sm);
  padding: 0.75rem 1rem;
  color: var(--text-primary);
  font-size: 0.9375rem;
  transition: border-color var(--transition-fast);
}

.form-input::placeholder,
.form-textarea::placeholder {
  color: var(--text-secondary);
}

.form-input:focus,
.form-textarea:focus {
  outline: none;
  border-color: rgba(255, 255, 255, 0.3);
}

.form-textarea {
  resize: vertical;
  min-height: 120px;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  .nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    flex-direction: column;
    background-color: rgba(10, 10, 10, 0.97);
    backdrop-filter: blur(12px);
    padding: var(--space-lg);
    gap: var(--space-md);
    border-bottom: 1px solid var(--border-subtle);
    transform: translateY(-100%);
    opacity: 0;
    pointer-events: none;
    transition: all var(--transition-normal);
  }

  .nav.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: all;
  }

  .nav-link {
    font-size: 1rem;
    padding: var(--space-xs) 0;
  }

  .header-actions {
    display: none;
  }

  .mobile-download {
    display: block;
    padding-top: var(--space-xs);
  }

  .hamburger {
    display: flex;
  }

  /* Hero */
  .hero {
    min-height: auto;
    padding: var(--space-3xl) 0 var(--space-2xl);
  }

  .hero-container {
    flex-direction: column;
    gap: var(--space-lg);
    padding: 0 var(--space-md);
  }

  .hero-content {
    max-width: 100%;
  }

  /* Rectangle ads: full-width below content on mobile */
  .ad-slot-rectangle {
    width: 100%;
    height: 200px;
  }

  /* Prose section stacks: text first, ads below */
  .prose-with-ads {
    flex-direction: column;
  }

  .prose-ads {
    flex-direction: row;
    flex-wrap: wrap;
    width: 100%;
  }

  /* Sections */
  .section {
    padding: var(--space-2xl) 0;
  }

  .download-section {
    padding: var(--space-2xl) 0;
  }

  /* Download button full width */
  .download-cta .btn-lg {
    width: 100%;
    max-width: 360px;
  }

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

  /* Toast */
  .download-toast {
    left: 16px;
    right: 16px;
    top: 16px;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--space-sm);
  }

  .header-container {
    padding: 0 var(--space-sm);
  }

  .footer-links {
    flex-direction: column;
    gap: var(--space-sm);
  }

  .hero-container {
    padding: 0 var(--space-sm);
  }

  .download-warning {
    font-size: 0.8125rem;
  }
}