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

:root {
  --color-primary: #6366F1;
  --color-primary-soft: #818CF8;
  --color-primary-pale: #E0E7FF;
  --color-accent: #10B981;
  --color-text: #18181B;
  --color-text-secondary: #52525B;
  --color-text-muted: #71717A;
  --color-bg: #FAFAFA;
  --color-bg-alt: #F4F4F5;
  --color-white: #FFFFFF;
  --color-border: #E4E4E7;

  --color-easy: #16A34A;
  --color-medium: #CA8A04;
  --color-hard: #DC2626;
  --color-expert: #7C3AED;

  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --container-width: 1100px;
  --border-radius: 12px;
  --border-radius-lg: 16px;
}

html {
  scroll-behavior: smooth;
}

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

.container {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 24px;
}

/* Header */
.header {
  background: var(--color-white);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 20px;
  color: var(--color-text);
  text-decoration: none;
}

.logo-icon {
  font-size: 24px;
  color: var(--color-primary);
}

.nav {
  display: flex;
  gap: 32px;
}

.nav a {
  color: var(--color-text-secondary);
  text-decoration: none;
  font-weight: 500;
  font-size: 14px;
  transition: color 0.2s;
}

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

/* Hero Section */
.hero {
  padding: 80px 0;
  text-align: center;
  background: linear-gradient(180deg, var(--color-white) 0%, var(--color-bg) 100%);
}

.hero h1 {
  font-size: 56px;
  font-weight: 700;
  margin-bottom: 16px;
  letter-spacing: -1px;
}

.hero .tagline {
  font-size: 20px;
  color: var(--color-text-secondary);
  margin-bottom: 24px;
}

.hero .description {
  max-width: 600px;
  margin: 0 auto 32px;
  color: var(--color-text-muted);
}

.app-badges {
  display: flex;
  justify-content: center;
  gap: 16px;
}

.badge img {
  height: 40px;
}

/* Sections */
.section {
  padding: 64px 0;
}

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

.section h2 {
  font-size: 32px;
  font-weight: 700;
  margin-bottom: 16px;
  text-align: center;
}

.section-intro {
  text-align: center;
  color: var(--color-text-secondary);
  margin-bottom: 40px;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

/* Rules Grid */
.rules-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 20px;
  margin-top: 40px;
}

.rule-card {
  background: var(--color-white);
  border-radius: var(--border-radius-lg);
  padding: 24px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
  border: 1px solid var(--color-border);
}

.rule-number {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--color-primary-pale);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 14px;
  margin-bottom: 12px;
}

.rule-card p {
  color: var(--color-text-secondary);
}

.rule-card strong {
  color: var(--color-text);
}

/* Rules Content with Diagram */
.rules-content {
  display: flex;
  gap: 48px;
  align-items: flex-start;
  margin-top: 40px;
}

.rules-content .rules-grid {
  flex: 1;
  min-width: 0;
  margin-top: 0;
}

.rules-diagram {
  flex: 0 0 auto;
  text-align: center;
}

.rules-diagram svg {
  display: block;
  max-width: 100%;
  height: auto;
}

.diagram-caption {
  margin-top: 12px;
  font-size: 14px;
  color: var(--color-text-muted);
}

/* Controls */
.controls-grid {
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-width: 500px;
  margin: 40px auto 0;
}

.control-item {
  display: flex;
  align-items: flex-start;
  gap: 16px;
}

.control-icon {
  width: 56px;
  height: 36px;
  border-radius: 8px;
  background: var(--color-bg-alt);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  font-weight: 600;
  color: var(--color-text-secondary);
  flex-shrink: 0;
}

.control-text {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.control-text strong {
  font-weight: 600;
}

.control-text span {
  color: var(--color-text-muted);
  font-size: 14px;
}

/* Techniques */
.techniques-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-width: 900px;
  margin: 0 auto;
}

.technique-card {
  background: var(--color-white);
  border-radius: var(--border-radius-lg);
  padding: 20px 24px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
  border: 1px solid var(--color-border);
}

.technique-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 12px;
}

.technique-number {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--color-bg-alt);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 13px;
  color: var(--color-text-secondary);
}

.technique-header h3 {
  font-size: 18px;
  font-weight: 600;
  flex: 1;
}

.difficulty-badge {
  padding: 4px 10px;
  border-radius: 6px;
  font-size: 12px;
  font-weight: 600;
}

.difficulty-badge.easy {
  background: rgba(22, 163, 74, 0.1);
  color: var(--color-easy);
}

.difficulty-badge.medium {
  background: rgba(202, 138, 4, 0.1);
  color: var(--color-medium);
}

.difficulty-badge.hard {
  background: rgba(220, 38, 38, 0.1);
  color: var(--color-hard);
}

.difficulty-badge.expert {
  background: rgba(124, 58, 237, 0.1);
  color: var(--color-expert);
}

.technique-card p {
  color: var(--color-text-secondary);
  font-size: 15px;
  line-height: 1.6;
}

.technique-content {
  display: flex;
  gap: 24px;
  align-items: flex-start;
}

.technique-content p {
  flex: 1;
  min-width: 0;
}

.technique-diagram {
  flex: 0 0 auto;
}

.technique-diagram svg {
  display: block;
  max-width: 100%;
  height: auto;
}

/* Tips */
.tips-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 16px;
  margin-top: 40px;
}

.tip-card {
  background: var(--color-bg);
  border-radius: var(--border-radius);
  padding: 20px;
  border: 1px solid var(--color-border);
}

.tip-card strong {
  display: block;
  margin-bottom: 8px;
  color: var(--color-text);
}

.tip-card p {
  color: var(--color-text-muted);
  font-size: 14px;
  margin: 0;
}

/* Difficulty Table */
.difficulty-table {
  max-width: 600px;
  margin: 40px auto 0;
  background: var(--color-white);
  border-radius: var(--border-radius-lg);
  overflow: hidden;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
  border: 1px solid var(--color-border);
}

.difficulty-row {
  display: flex;
  align-items: flex-start;
  padding: 16px 20px;
  border-bottom: 1px solid var(--color-border);
}

.difficulty-row:last-child {
  border-bottom: none;
}

.difficulty-row.master {
  background: var(--color-bg);
  border-top: 2px solid var(--color-border);
}

.difficulty-name {
  width: 80px;
  font-weight: 600;
  flex-shrink: 0;
}

.difficulty-desc {
  color: var(--color-text-secondary);
  font-size: 14px;
}

.note {
  text-align: center;
  color: var(--color-text-muted);
  font-size: 14px;
  margin-top: 24px;
}

/* Footer */
.footer {
  background: var(--color-text);
  color: var(--color-white);
  padding: 48px 0;
  margin-top: 64px;
}

.footer-content {
  text-align: center;
}

.footer-brand {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-weight: 600;
  font-size: 18px;
  margin-bottom: 24px;
}

.footer-brand .logo-icon {
  color: var(--color-primary-soft);
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 32px;
  margin-bottom: 24px;
}

.footer-links a {
  color: rgba(255, 255, 255, 0.7);
  text-decoration: none;
  font-size: 14px;
  transition: color 0.2s;
}

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

.copyright {
  color: rgba(255, 255, 255, 0.5);
  font-size: 13px;
}

/* Legal Pages */
.legal-page {
  padding: 64px 0;
}

.legal-page h1 {
  font-size: 36px;
  margin-bottom: 8px;
}

.legal-page .last-updated {
  color: var(--color-text-muted);
  margin-bottom: 40px;
}

.legal-page h2 {
  font-size: 20px;
  margin-top: 32px;
  margin-bottom: 16px;
  text-align: left;
}

.legal-page p,
.legal-page ul {
  color: var(--color-text-secondary);
  margin-bottom: 16px;
}

.legal-page ul {
  padding-left: 24px;
}

.legal-page li {
  margin-bottom: 8px;
}

.legal-page a {
  color: var(--color-primary);
}

/* Responsive */
@media (max-width: 768px) {
  .header .container {
    flex-direction: column;
    height: auto;
    padding: 16px 24px;
    gap: 16px;
  }

  .nav {
    gap: 20px;
    flex-wrap: wrap;
    justify-content: center;
  }

  .hero {
    padding: 48px 0;
  }

  .hero h1 {
    font-size: 40px;
  }

  .hero .tagline {
    font-size: 18px;
  }

  .section {
    padding: 48px 0;
  }

  .section h2 {
    font-size: 28px;
  }

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

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

  .technique-header {
    flex-wrap: wrap;
  }

  .difficulty-row {
    flex-direction: column;
    gap: 4px;
  }

  .difficulty-name {
    width: auto;
  }

  .rules-content {
    flex-direction: column;
    gap: 32px;
  }

  .rules-diagram {
    order: -1;
    margin: 0 auto;
  }

  .technique-content {
    flex-direction: column;
    gap: 16px;
  }

  .technique-diagram {
    margin: 0 auto;
  }
}