/* Global Design System - Light Mode */
@import url('https://fonts.googleapis.com/css2?family=Outfit:wght@300;400;500;600;700;800;900&display=swap');

:root {
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  
  --color-sudoku: #3B82F6;
  --color-sudoku-light: #60a5fa;
  --color-accent: #6c5ce7;
  --color-accent-hover: #5b4cc4;
  --color-accent-light: rgba(108, 92, 231, 0.1);
  --color-elite: #f59e0b;
  --color-elite-glow: rgba(245, 158, 11, 0.15);
  --color-error: #ef4444;
  --color-success: #10b981;
  
  --border-color: rgba(226, 232, 240, 0.8);
  --border-focus: #3B82F6;
  
  --card-shadow: 0 10px 30px rgba(15, 23, 42, 0.04);
  --hover-shadow: 0 20px 40px rgba(15, 23, 42, 0.08);
  --device-shadow: 0 25px 60px rgba(15, 23, 42, 0.12);
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --max-width: 1200px;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

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

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

/* Header & Navigation */
header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  background-color: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
  transition: var(--transition);
}

header.scrolled {
  background-color: var(--bg-secondary);
  box-shadow: var(--card-shadow);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1.25rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo-link {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.45rem;
  font-weight: 800;
  color: var(--text-primary);
  letter-spacing: -0.5px;
}

.logo-link img {
  width: 34px;
  height: 34px;
  border-radius: 8px;
  box-shadow: 0 4px 10px rgba(59, 130, 246, 0.2);
}

.logo-accent {
  color: var(--color-sudoku);
}

/* Toggle Menu Button */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: space-between;
  width: 24px;
  height: 18px;
  background: transparent;
  border: none;
  cursor: pointer;
  z-index: 1001;
}

.nav-toggle span {
  width: 100%;
  height: 2px;
  background-color: var(--text-primary);
  border-radius: 2px;
  transition: var(--transition);
}

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

.nav-links a {
  font-weight: 500;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.nav-links a:hover, .nav-links a.active {
  color: var(--color-sudoku);
}

.nav-links a.active {
  font-weight: 600;
}

/* Download buttons styling */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.8rem;
  background-color: var(--text-primary);
  color: #fff;
  padding: 0.8rem 1.8rem;
  border-radius: 12px;
  font-weight: 600;
  font-size: 0.95rem;
  box-shadow: 0 4px 15px rgba(15, 23, 42, 0.15);
  transition: var(--transition);
  cursor: pointer;
}

.btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 25px rgba(15, 23, 42, 0.25);
  color: #fff;
}

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

.btn-secondary:hover {
  background: var(--bg-primary);
  box-shadow: var(--hover-shadow);
}

/* Hero Section */
.hero {
  display: flex;
  align-items: center;
  gap: 4rem;
  min-height: 90vh;
  padding: 8rem 2rem 4rem;
  max-width: var(--max-width);
  margin: 0 auto;
}

.hero-content {
  flex: 1.1;
  text-align: left;
}

.hero-tagline {
  display: inline-block;
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.08), rgba(108, 92, 231, 0.08));
  color: var(--color-accent);
  padding: 0.5rem 1.2rem;
  border-radius: 30px;
  font-weight: 600;
  font-size: 0.9rem;
  margin-bottom: 1.5rem;
  letter-spacing: 0.5px;
}

.hero h1 {
  font-size: 3.6rem;
  font-weight: 900;
  line-height: 1.1;
  margin-bottom: 1.5rem;
  letter-spacing: -1.5px;
}

.hero h1 span {
  background: linear-gradient(135deg, var(--color-sudoku), var(--color-accent));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-description {
  font-size: 1.12rem;
  color: var(--text-secondary);
  margin-bottom: 2.5rem;
  max-width: 560px;
  line-height: 1.6;
}

.download-buttons {
  display: flex;
  gap: 1.2rem;
  flex-wrap: wrap;
}

.hero-visual {
  flex: 0.9;
  display: flex;
  justify-content: center;
  align-items: center;
  position: relative;
}

/* Device Mockup phone frame */
.device-mockup {
  width: 325px;
  height: 650px;
  background-color: var(--bg-secondary);
  border: 12px solid var(--text-primary);
  border-radius: 40px;
  box-shadow: var(--device-shadow);
  position: relative;
  overflow: hidden;
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
}

.device-screen-header {
  text-align: center;
  margin-bottom: 1rem;
}

.device-screen-header h2 {
  font-size: 1.1rem;
  font-weight: 800;
  letter-spacing: 1px;
  color: var(--text-primary);
}

.device-scoreboard {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.4rem 0.8rem;
  background: var(--bg-primary);
  border-radius: 10px;
  font-size: 0.8rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
  border: 1px solid var(--border-color);
}

.device-opponent {
  display: flex;
  align-items: center;
  gap: 4px;
  color: var(--color-error);
}

.device-opponent span {
  width: 6px;
  height: 6px;
  background: var(--color-error);
  border-radius: 50%;
  display: inline-block;
}

.device-timer {
  color: var(--color-sudoku);
}

/* 9x9 Sudoku Simulation Grid */
.device-sudoku-grid {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  border: 2px solid var(--text-primary);
  background-color: var(--text-primary);
  border-radius: 8px;
  overflow: hidden;
  margin-bottom: 0.75rem;
  box-shadow: var(--card-shadow);
}

.device-cell {
  aspect-ratio: 1;
  background-color: var(--bg-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 0.82rem;
  color: var(--text-secondary);
  border: 0.5px solid rgba(226, 232, 240, 0.8);
  user-select: none;
  transition: var(--transition);
}

/* Thicker borders for 3x3 blocks */
.device-cell:nth-child(3n) {
  border-right: 2px solid var(--text-primary);
}
.device-cell:nth-child(9n) {
  border-right: none;
}
.device-sudoku-grid > .device-cell:nth-child(n+19):nth-child(-n+27),
.device-sudoku-grid > .device-cell:nth-child(n+46):nth-child(-n+54) {
  border-bottom: 2px solid var(--text-primary);
}

.device-cell.prefilled {
  color: var(--text-primary);
}

.device-cell.solve-flash {
  background-color: rgba(16, 185, 129, 0.15);
  color: var(--color-success);
}

.device-cell.blurred {
  filter: blur(2.5px);
  opacity: 0.35;
  background-color: var(--bg-primary);
  pointer-events: none;
}

.device-status-banner {
  text-align: center;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--text-secondary);
  margin-bottom: 0.75rem;
  min-height: 1.2rem;
}

/* Keypad Grid Mockup */
.device-keypad {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  gap: 4px;
  margin-top: auto;
}

.device-key {
  aspect-ratio: 1;
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.8rem;
  color: var(--text-primary);
  transition: var(--transition);
}

.device-key.locked {
  background-color: rgba(59, 130, 246, 0.1);
  border-color: var(--color-sudoku);
  color: var(--color-sudoku);
  position: relative;
  font-size: 0.65rem;
}

.device-key.locked::after {
  content: '🧊';
  position: absolute;
  font-size: 0.5rem;
  top: 1px;
  right: 1px;
}

/* Sections Base Styling */
section {
  padding: 5rem 2rem;
}

.section-title {
  font-size: 2.5rem;
  font-weight: 800;
  text-align: center;
  margin-bottom: 3.5rem;
  letter-spacing: -1px;
}

.section-title span {
  background: linear-gradient(135deg, var(--color-sudoku), var(--color-accent));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Features Section */
#features {
  max-width: var(--max-width);
  margin: 0 auto;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2.5rem;
}

.feature-card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  padding: 3rem 2rem;
  border-radius: 20px;
  box-shadow: var(--card-shadow);
  transition: var(--transition);
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  position: relative;
  overflow: hidden;
}

.feature-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--hover-shadow);
  border-color: rgba(59, 130, 246, 0.3);
}

.feature-icon {
  width: 54px;
  height: 54px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
}

.feature-card.f-classic .feature-icon {
  background: linear-gradient(135deg, var(--color-sudoku), var(--color-sudoku-light));
  color: #fff;
}

.feature-card.f-blitz .feature-icon {
  background: linear-gradient(135deg, var(--color-accent), #a8a5e6);
  color: #fff;
}

.feature-card.f-elite .feature-icon {
  background: linear-gradient(135deg, var(--color-elite), #fbbf24);
  color: #fff;
}

.feature-card h3 {
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: -0.5px;
}

.feature-card p {
  color: var(--text-secondary);
  font-size: 0.96rem;
  line-height: 1.6;
}

/* Support Form Section */
#support {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}

.support-container {
  max-width: 600px;
  margin: 0 auto;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 24px;
  padding: 3.5rem 2.5rem;
  box-shadow: var(--card-shadow);
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-group label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.5rem;
  font-size: 0.9rem;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 0.9rem 1.2rem;
  border: 1px solid var(--border-color);
  border-radius: 10px;
  font-family: inherit;
  font-size: 0.95rem;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  transition: var(--transition);
}

.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--color-sudoku);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

.btn-submit {
  width: 100%;
  border: none;
  justify-content: center;
  padding: 1rem;
  background-color: var(--color-sudoku);
}

.btn-submit:hover {
  background-color: #2563eb;
}

/* Legal & Rules Pages layout */
.legal-page, .rules-page {
  max-width: 800px;
  margin: 0 auto;
  padding: 10rem 2rem 5rem;
}

.legal-meta {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: 2.5rem;
}

.legal-content h2, .rules-content h2 {
  font-size: 1.45rem;
  font-weight: 700;
  margin-top: 2.5rem;
  margin-bottom: 1rem;
  letter-spacing: -0.5px;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.legal-content p, .rules-content p {
  margin-bottom: 1.25rem;
  color: var(--text-secondary);
  font-size: 1.02rem;
  line-height: 1.7;
}

.legal-content ul, .rules-content ul {
  margin-left: 1.5rem;
  margin-bottom: 1.5rem;
  color: var(--text-secondary);
}

.legal-content li, .rules-content li {
  margin-bottom: 0.6rem;
  font-size: 1rem;
}

.rules-note {
  background-color: var(--bg-primary);
  border-left: 4px solid var(--color-sudoku);
  padding: 1.25rem 1.5rem;
  border-radius: 0 12px 12px 0;
  margin: 2rem 0;
}

.rules-note h4 {
  font-weight: 700;
  margin-bottom: 0.35rem;
  color: var(--text-primary);
}

.rules-table {
  width: 100%;
  border-collapse: collapse;
  margin: 2rem 0;
  font-size: 0.95rem;
  box-shadow: var(--card-shadow);
  border-radius: 12px;
  overflow: hidden;
  border: 1px solid var(--border-color);
}

.rules-table th, .rules-table td {
  padding: 1rem;
  text-align: left;
}

.rules-table th {
  background-color: var(--text-primary);
  color: #fff;
  font-weight: 600;
}

.rules-table td {
  background-color: var(--bg-secondary);
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border-color);
}

.rules-table tr:last-child td {
  border-bottom: none;
}

/* Footer Section */
footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 4rem 2rem 2.5rem;
  margin-top: 5rem;
}

.footer-grid {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 4rem;
  margin-bottom: 3.5rem;
}

.footer-info {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
}

.footer-logo {
  font-weight: 900;
  font-size: 1.5rem;
  letter-spacing: -0.5px;
  color: var(--text-primary);
}

.footer-desc {
  color: var(--text-secondary);
  font-size: 0.95rem;
  max-width: 340px;
  line-height: 1.6;
}

.footer-links-col h4 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 1.2rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--text-primary);
}

.footer-links-col ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}

.footer-links-col a {
  color: var(--text-secondary);
  font-size: 0.92rem;
}

.footer-links-col a:hover {
  color: var(--color-sudoku);
  padding-left: 4px;
}

.footer-bottom {
  max-width: var(--max-width);
  margin: 0 auto;
  border-top: 1px solid var(--border-color);
  padding-top: 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--text-muted);
  font-size: 0.85rem;
  flex-wrap: wrap;
  gap: 1rem;
}

/* Responsive Breakpoints */
@media (max-width: 992px) {
  .hero {
    flex-direction: column-reverse;
    text-align: center;
    gap: 3.5rem;
    padding-top: 7rem;
  }
  .hero-content {
    display: flex;
    flex-direction: column;
    align-items: center;
  }
  .hero-description {
    text-align: center;
  }
  .download-buttons {
    justify-content: center;
  }
  .footer-grid {
    grid-template-columns: 1fr;
    gap: 2.5rem;
  }
}

@media (max-width: 768px) {
  .hero h1 {
    font-size: 2.6rem;
  }
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    flex-direction: column;
    padding: 2rem;
    gap: 1.5rem;
    box-shadow: 0 15px 25px rgba(0,0,0,0.05);
  }
  .nav-links.active {
    display: flex;
  }
  .nav-toggle {
    display: flex;
  }
  .nav-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
  }
  .nav-toggle.active span:nth-child(2) {
    opacity: 0;
  }
  .nav-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(6px, -6px);
  }
  .legal-page, .rules-page {
    padding-top: 8rem;
  }
}