/* ============================================
   PapyStudio Landing Page Styles
   Shared styles for index.html, markdowntab.html, website-index.html
   ============================================ */

/* --- Variables --- */
:root {
  --bg: #fafafa;
  --bg-alt: #f3f4f6;
  --text: #111827;
  --text-secondary: #6b7280;
  --text-muted: #9ca3af;
  --accent: #21786D;
  --accent-hover: #1a6359;
  --accent-light: #e8f5f2;
  --border: #e5e7eb;
  --card-bg: #ffffff;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-lg: 0 10px 25px rgba(0,0,0,0.08), 0 4px 10px rgba(0,0,0,0.04);
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --space-3xl: 64px;
  --max-width: 1120px;
  --header-height: 64px;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-serif: 'Noto Serif SC', serif;
  --transition: 0.2s ease;
}

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

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

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
}

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

img, svg {
  display: block;
  max-width: 100%;
}

/* --- Header --- */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  z-index: 100;
  background: rgba(250, 250, 250, 0.8);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

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

.nav-logo {
  font-weight: 700;
  font-size: 18px;
  letter-spacing: -0.02em;
}

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

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

.nav-link {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-secondary);
  transition: all var(--transition);
  padding: 6px 12px;
  border-radius: var(--radius-sm);
}

.nav-link:hover {
  color: var(--text);
  background: rgba(33, 120, 109, 0.06);
}

.nav-link.active {
  color: var(--accent);
  background: rgba(33, 120, 109, 0.1);
}

.nav-btn {
  font-size: 14px;
  font-weight: 500;
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-sm);
  background: var(--accent);
  color: white;
  transition: background var(--transition);
}

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

/* --- Hero --- */
.hero {
  position: relative;
  min-height: 80vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: calc(var(--header-height) + var(--space-3xl)) var(--space-lg) var(--space-3xl);
  overflow: hidden;
}

.hero-content {
  position: relative;
  z-index: 2;
  max-width: 720px;
}

.hero-label {
  font-size: 13px;
  font-weight: 500;
  color: var(--accent);
  background: var(--accent-light);
  display: inline-block;
  padding: var(--space-xs) var(--space-md);
  border-radius: 999px;
  margin-bottom: var(--space-lg);
}

.hero-title {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  margin-bottom: var(--space-xl);
}

.hero-title-main {
  font-family: var(--font-serif);
  font-size: clamp(2.5rem, 6vw, 4rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.02em;
}

.hero-title-sub {
  font-size: clamp(1.25rem, 3vw, 1.75rem);
  font-weight: 400;
  color: var(--text-secondary);
}

.hero-desc {
  font-size: 1.125rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-xl);
}

.hero-cta {
  display: flex;
  justify-content: center;
  gap: var(--space-md);
}

.hero-bg {
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at 50% 0%, rgba(99, 102, 241, 0.08) 0%, transparent 60%);
  pointer-events: none;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 15px;
  font-weight: 500;
  padding: var(--space-md) var(--space-xl);
  border-radius: var(--radius);
  transition: all var(--transition);
  cursor: pointer;
  border: none;
}

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

.btn-primary:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
  box-shadow: var(--shadow-lg);
}

.btn-outline {
  background: transparent;
  border: 1.5px solid var(--accent);
  color: var(--accent);
  transition: all var(--transition);
}

.btn-outline:hover {
  background: var(--accent);
  color: white;
  border-color: var(--accent);
  transform: translateY(-1px);
  box-shadow: var(--shadow-lg);
}

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

.section-alt {
  background: var(--bg-alt);
}

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

.section-header {
  text-align: center;
  margin-bottom: var(--space-2xl);
}

.section-label {
  font-size: 13px;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: var(--space-sm);
}

.section-title {
  font-family: var(--font-serif);
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: var(--space-md);
}

.section-desc {
  font-size: 1.0625rem;
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto;
}

/* --- Preview --- */
.preview-image {
  max-width: 960px;
  margin: 0 auto;
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border);
}

.preview-image img {
  display: block;
  width: 100%;
  height: auto;
}

/* --- Problems Grid --- */
.problems-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-lg);
}

.problem-card {
  background: var(--card-bg);
  padding: var(--space-xl);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  transition: all var(--transition);
}

.problem-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.problem-num {
  font-size: 13px;
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-light);
  display: inline-block;
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-sm);
  margin-bottom: var(--space-md);
}

.problem-card .problem-title {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
}

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

/* --- Features Grid --- */
.features-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-lg);
}

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

.feature-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.fc-icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-light);
  color: var(--accent);
  border-radius: var(--radius-sm);
  margin-bottom: var(--space-md);
}

.feature-card h3 {
  font-size: 1.0625rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
}

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

/* --- Products Grid --- */
.products-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: var(--space-xl);
}

.product-card {
  display: flex;
  flex-direction: column;
  background: var(--card-bg);
  padding: var(--space-xl);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  transition: all var(--transition);
}

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

.product-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-md);
}

.product-logo {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-light);
  color: var(--accent);
  border-radius: var(--radius-sm);
}

.product-logo-img {
  width: 32px;
  height: 32px;
}

.product-logo-markdowntab {
  font-size: 24px;
}

.product-badge {
  font-size: 11px;
  font-weight: 600;
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-sm);
  background: var(--bg-alt);
  color: var(--text-secondary);
}

.product-badge-extension {
  background: #fef3c7;
  color: #92400e;
}

.product-name {
  font-size: 1.375rem;
  font-weight: 700;
  margin-bottom: var(--space-xs);
}

.product-tagline {
  font-size: 0.9375rem;
  color: var(--accent);
  font-weight: 500;
  margin-bottom: var(--space-md);
}

.product-desc {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: var(--space-md);
  flex-grow: 1;
}

.product-features {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin-bottom: var(--space-lg);
}

.pf-tag {
  font-size: 12px;
  font-weight: 500;
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-sm);
  background: var(--bg-alt);
  color: var(--text-secondary);
}

.product-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 14px;
  font-weight: 600;
  color: var(--accent);
  transition: gap var(--transition);
}

.product-card:hover .product-link {
  gap: var(--space-md);
}

/* --- Philosophy --- */
.philosophy-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
  max-width: 720px;
  margin: 0 auto;
}

.phil-item {
  display: flex;
  gap: var(--space-lg);
  padding: var(--space-xl);
  background: var(--card-bg);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.phil-num {
  font-size: 13px;
  font-weight: 700;
  color: var(--accent);
  background: var(--accent-light);
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-sm);
  flex-shrink: 0;
  height: fit-content;
}

.phil-content h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
}

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

/* --- Install --- */
.install-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}

.install-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: var(--space-xl);
  background: var(--card-bg);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  transition: all var(--transition);
}

.install-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
  border-color: var(--accent);
}

.install-icon {
  width: 56px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-light);
  color: var(--accent);
  border-radius: 50%;
  margin-bottom: var(--space-md);
}

.install-card h3 {
  font-size: 1.0625rem;
  font-weight: 600;
  margin-bottom: var(--space-xs);
}

.install-card p {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-md);
}

.install-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 14px;
  font-weight: 600;
  color: var(--accent);
  transition: gap var(--transition);
}

.install-card:hover .install-link {
  gap: var(--space-md);
}

/* --- Steps --- */
.steps-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-lg);
}

.step-card {
  text-align: center;
  padding: var(--space-xl);
}

.step-num {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent);
  color: white;
  font-size: 1.25rem;
  font-weight: 700;
  border-radius: 50%;
  margin: 0 auto var(--space-md);
}

.step-card h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
}

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

/* --- Tech Grid --- */
.tech-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-md);
}

.tech-card {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-md) var(--space-lg);
  background: var(--card-bg);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
}

.tech-name {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.tech-val {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text);
}

/* --- Use Cases --- */
.use-cases {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-sm);
}

.use-tag {
  font-size: 13px;
  font-weight: 500;
  padding: var(--space-sm) var(--space-md);
  border-radius: 999px;
  background: var(--card-bg);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  transition: all var(--transition);
}

.use-tag:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* --- CTA --- */
.section-cta {
  text-align: center;
}

.cta-content {
  max-width: 640px;
  margin: 0 auto;
}

.cta-title {
  font-family: var(--font-serif);
  font-size: clamp(1.5rem, 4vw, 2.25rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: var(--space-md);
}

.cta-desc {
  font-size: 1.0625rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
}

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

/* --- Footer --- */
.footer {
  padding: var(--space-2xl) var(--space-lg);
  border-top: 1px solid var(--border);
  background: var(--bg-alt);
}

.footer-content {
  max-width: var(--max-width);
  margin: 0 auto;
  text-align: center;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-xs);
  margin-bottom: var(--space-md);
}

.footer-logo {
  font-weight: 700;
  font-size: 18px;
  background: linear-gradient(135deg, var(--accent), #8b5cf6);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.footer-tagline {
  font-size: 13px;
  color: var(--text-muted);
}

.footer-contact {
  margin: var(--space-sm) 0;
}

.footer-email {
  font-size: 13px;
  color: var(--text-secondary);
  transition: color var(--transition);
}

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

.footer-copy {
  font-size: 13px;
  color: var(--text-muted);
}

/* --- Animations --- */
.fade-up {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-up.visible {
  opacity: 1;
  transform: translateY(0);
}

.delay-1 { transition-delay: 0.1s; }
.delay-2 { transition-delay: 0.2s; }
.delay-3 { transition-delay: 0.3s; }
.delay-4 { transition-delay: 0.4s; }

/* --- Responsive --- */
@media (max-width: 768px) {
  .nav-links {
    gap: var(--space-md);
  }

  .hero {
    min-height: 70vh;
    padding-top: calc(var(--header-height) + var(--space-2xl));
  }

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

  .problems-grid,
  .products-grid,
  .steps-grid,
  .tech-grid,
  .install-grid {
    grid-template-columns: 1fr;
  }

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

  .phil-item {
    flex-direction: column;
    gap: var(--space-md);
  }
}