/* ==============================
   FoldNotes Website
   ============================== */

:root {
  --color-bg: #FAFAF9;
  --color-surface: #FFFFFF;
  --color-text: #1A1A1A;
  --color-text-secondary: #6B6B6B;
  --color-accent: #2563EB;
  --color-accent-hover: #1D4ED8;
  --color-border: #E5E5E5;
  --color-code-bg: #F3F4F6;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --max-width: 1120px;
  --radius: 12px;
  --radius-sm: 8px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #0F0F0F;
    --color-surface: #1A1A1A;
    --color-text: #F0F0F0;
    --color-text-secondary: #999999;
    --color-accent: #60A5FA;
    --color-accent-hover: #93C5FD;
    --color-border: #2A2A2A;
    --color-code-bg: #1F1F1F;
  }
}

/* Reset */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; -webkit-font-smoothing: antialiased; }
body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
}
a { color: var(--color-accent); text-decoration: none; }
a:hover { color: var(--color-accent-hover); }
img { max-width: 100%; height: auto; }

/* ==============================
   Header
   ============================== */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem;
  height: 64px;
  display: flex;
  align-items: center;
  gap: 2rem;
}

.logo { display: flex; align-items: center; gap: 0.5rem; text-decoration: none; }
.logo-icon { border-radius: 6px; }
.logo-text {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 1.5rem;
  margin-left: auto;
}
.nav-links a {
  color: var(--color-text-secondary);
  font-size: 0.9375rem;
  font-weight: 500;
  transition: color 0.15s;
}
.nav-links a:hover,
.nav-links a.active { color: var(--color-text); }
.external-icon { font-size: 0.75rem; }

.nav-cta {
  font-size: 0.875rem;
  font-weight: 600;
  padding: 0.5rem 1.25rem;
  background: var(--color-accent);
  color: #FFF !important;
  border-radius: var(--radius-sm);
  transition: background 0.15s;
  white-space: nowrap;
}
.nav-cta:hover { background: var(--color-accent-hover); }

/* ==============================
   Hero
   ============================== */

.hero {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 6rem 2rem 4rem;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
}

.hero h1 {
  font-size: 3.5rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: 0.75rem;
}

.hero-byline {
  font-size: 1.5rem;
  font-weight: 500;
  color: var(--color-accent);
  letter-spacing: -0.01em;
  margin-bottom: 1.5rem;
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 2rem;
  max-width: 480px;
}

.hero-actions {
  display: flex;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

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

.hero-screenshot {
  width: 100%;
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.08);
}

/* ==============================
   Buttons
   ============================== */

.btn {
  display: inline-block;
  font-size: 1rem;
  font-weight: 600;
  padding: 0.75rem 1.75rem;
  border-radius: var(--radius-sm);
  border: none;
  cursor: pointer;
  transition: all 0.15s;
}

.btn-primary {
  background: var(--color-accent);
  color: #FFF !important;
}
.btn-primary:hover { background: var(--color-accent-hover); }

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

/* ==============================
   Features Overview (Home)
   ============================== */

.features-overview {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 4rem 2rem 6rem;
}

.features-overview h2 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  text-align: center;
  margin-bottom: 3rem;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

.feature-card {
  padding: 2rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  transition: border-color 0.2s;
}
.feature-card:hover { border-color: var(--color-accent); }

.feature-icon {
  font-size: 1.75rem;
  margin-bottom: 1rem;
  color: var(--color-accent);
}

.feature-card h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

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

/* ==============================
   Features Page
   ============================== */

.features-hero {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 5rem 2rem 3rem;
  text-align: center;
}

.features-hero h1 {
  font-size: 2.75rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 1rem;
}

.features-hero > p {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  max-width: 640px;
  margin: 0 auto;
  line-height: 1.6;
}

/* Feature Wall */

.feature-wall {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2rem 2rem 4rem;
}

.wall-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--color-border);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
}

.wall-item {
  display: flex;
  gap: 0.75rem;
  padding: 1.25rem 1.5rem;
  background: var(--color-surface);
  align-items: flex-start;
  transition: background 0.15s;
}

.wall-item:hover {
  background: var(--color-bg);
}

.wall-check {
  color: var(--color-accent);
  font-size: 1.125rem;
  font-weight: 600;
  line-height: 1.4;
  flex-shrink: 0;
}

.wall-item strong {
  display: block;
  font-size: 0.9375rem;
  font-weight: 600;
  margin-bottom: 0.2rem;
}

.wall-item span:not(.wall-check) {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
  line-height: 1.45;
}

.wall-item code {
  background: var(--color-code-bg);
  padding: 0.1em 0.35em;
  border-radius: 3px;
  font-size: 0.8em;
}

/* Features Detail (below the wall) */

.features-detail {
  max-width: 720px;
  margin: 0 auto;
  padding: 2rem 2rem 6rem;
}

.features-detail h2 {
  font-size: 1.5rem;
  font-weight: 600;
  margin-top: 3rem;
  margin-bottom: 1rem;
  padding-top: 2rem;
  border-top: 1px solid var(--color-border);
}

.features-detail h2:first-child {
  border-top: none;
  padding-top: 0;
}

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

.features-detail ul {
  margin-bottom: 1rem;
  padding-left: 1.5rem;
  color: var(--color-text-secondary);
}

.features-detail li { margin-bottom: 0.5rem; }

.features-detail code {
  background: var(--color-code-bg);
  padding: 0.15em 0.4em;
  border-radius: 4px;
  font-size: 0.875em;
}

.features-detail strong {
  color: var(--color-text);
}

/* ==============================
   CTA / Signup
   ============================== */

.cta-section {
  max-width: 640px;
  margin: 0 auto;
  padding: 4rem 2rem 6rem;
  text-align: center;
}

.cta-section h2 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
}

.cta-section > p {
  color: var(--color-text-secondary);
  font-size: 1.0625rem;
  margin-bottom: 2rem;
}

.signup-form form {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  max-width: 480px;
  margin: 0 auto 1rem;
}

.signup-form input[type="email"] {
  flex: 1;
  padding: 0.75rem 1rem;
  font-size: 1rem;
  font-family: var(--font-sans);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  color: var(--color-text);
  outline: none;
  transition: border-color 0.15s;
}
.signup-form input[type="email"]:focus {
  border-color: var(--color-accent);
}

.signup-form input[type="submit"] {
  font-family: var(--font-sans);
}

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

/* ==============================
   Page Content
   ============================== */

.page-content {
  max-width: 720px;
  margin: 0 auto;
  padding: 4rem 2rem 6rem;
}

.page-content h1 {
  font-size: 2.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 2rem;
}

.page-content h2 {
  font-size: 1.5rem;
  font-weight: 600;
  margin-top: 2.5rem;
  margin-bottom: 1rem;
}

.page-content h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-top: 2rem;
  margin-bottom: 0.75rem;
}

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

.page-content ul, .page-content ol {
  margin-bottom: 1rem;
  padding-left: 1.5rem;
  color: var(--color-text-secondary);
}

.page-content li { margin-bottom: 0.5rem; }

.page-content code {
  background: var(--color-code-bg);
  padding: 0.15em 0.4em;
  border-radius: 4px;
  font-size: 0.875em;
}

/* ==============================
   Blog
   ============================== */

.post-summary {
  padding: 2rem 0;
  border-bottom: 1px solid var(--color-border);
}
.post-summary:last-child { border-bottom: none; }

.post-summary h2 {
  font-size: 1.375rem;
  margin-top: 0;
  margin-bottom: 0.25rem;
}

.post-summary time {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
  display: block;
  margin-bottom: 0.5rem;
}

/* ==============================
   Footer
   ============================== */

.site-footer {
  border-top: 1px solid var(--color-border);
  padding: 4rem 0 2rem;
  margin-top: 2rem;
}

.footer-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem;
}

.footer-brand { margin-bottom: 2rem; display: flex; align-items: center; gap: 0.5rem; flex-wrap: wrap; }
.footer-tagline {
  color: var(--color-text-secondary);
  font-size: 0.9375rem;
  margin-top: 0.25rem;
  width: 100%;
}

.footer-links {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
  margin-bottom: 3rem;
}

.footer-col h4 {
  font-size: 0.8125rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-secondary);
  margin-bottom: 0.75rem;
}

.footer-col ul { list-style: none; }
.footer-col li { margin-bottom: 0.5rem; }
.footer-col a {
  color: var(--color-text);
  font-size: 0.9375rem;
}
.footer-col a:hover { color: var(--color-accent); }

.footer-bottom {
  border-top: 1px solid var(--color-border);
  padding-top: 1.5rem;
}
.footer-bottom p {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
}

.footer-trademarks {
  font-size: 0.6875rem;
  margin-top: 0.75rem;
  line-height: 1.5;
  opacity: 0.7;
}

/* ==============================
   Responsive
   ============================== */

@media (max-width: 768px) {
  .hero {
    grid-template-columns: 1fr;
    padding: 3rem 1.5rem 2rem;
    gap: 2rem;
  }
  .hero h1 { font-size: 2.5rem; }
  .hero-byline { font-size: 1.25rem; }
  .hero-subtitle { font-size: 1.0625rem; }
  .hero-actions { flex-direction: column; }

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

  .nav-links { display: none; }
  .nav-container { justify-content: space-between; }

  .signup-form form { flex-direction: column; }

  .footer-links { grid-template-columns: 1fr; gap: 1.5rem; }

  .features-hero h1 { font-size: 2rem; }
  .wall-grid { grid-template-columns: 1fr; }
}