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

:root {
  --bg: #0a0a0f;
  --surface: #1a1b23;
  --surface-light: #252630;
  --surface-dark: #131419;
  --primary: #4f46e5;
  --primary-light: #7c3aed;
  --primary-dark: #3730a3;
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-tertiary: #94a3b8;
  --success: #10b981;
  --warning: #f59e0b;
  --error: #ef4444;
  --info: #3b82f6;
  --accent: #ec4899;
  --border: #1e293b;
  --border-light: #334155;
  --gradient: linear-gradient(135deg, #4f46e5, #7c3aed);
  --radius-s: 4px;
  --radius-m: 8px;
  --radius-l: 12px;
  --radius-xl: 16px;
  --radius-xxl: 24px;
  --radius-round: 999px;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.6);
  --max-width: 768px;
  --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Hiragino Sans',
    'Noto Sans JP', sans-serif;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text-primary);
  line-height: 1.7;
  min-height: 100vh;
}

a {
  color: var(--primary-light);
  text-decoration: none;
  transition: color 0.2s ease;
}

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

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

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

header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 10, 15, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
}

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

.header-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--text-primary);
  font-weight: 700;
  font-size: 1.25rem;
  letter-spacing: -0.02em;
}

.header-brand img {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-m);
}

.lang-switch {
  display: flex;
  align-items: center;
  gap: 4px;
  font-size: 0.875rem;
  font-weight: 600;
}

.lang-switch a {
  padding: 6px 12px;
  border-radius: var(--radius-m);
  color: var(--text-tertiary);
  transition: all 0.2s ease;
}

.lang-switch a:hover {
  color: var(--text-primary);
  background: var(--surface);
}

.lang-switch a.active {
  color: var(--text-primary);
  background: var(--surface-light);
}

.lang-switch .separator {
  color: var(--border-light);
  user-select: none;
}

.hero {
  padding: 80px 0 64px;
  text-align: center;
}

.hero-icon {
  width: 96px;
  height: 96px;
  border-radius: var(--radius-xl);
  margin: 0 auto 32px;
  box-shadow: var(--shadow-lg), 0 0 60px rgba(79, 70, 229, 0.3);
}

.hero h1 {
  font-size: 2.25rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: 16px;
  background: var(--gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero .subtitle {
  font-size: 1.125rem;
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto 40px;
  line-height: 1.8;
}

.hero-actions {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 28px;
  border-radius: var(--radius-l);
  font-size: 1rem;
  font-weight: 600;
  font-family: var(--font);
  cursor: pointer;
  border: none;
  transition: all 0.2s ease;
  text-decoration: none;
}

.btn-primary {
  background: var(--gradient);
  color: #fff;
  box-shadow: 0 4px 16px rgba(79, 70, 229, 0.4);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(79, 70, 229, 0.5);
  color: #fff;
}

.btn-secondary {
  background: var(--surface);
  color: var(--text-primary);
  border: 1px solid var(--border-light);
}

.btn-secondary:hover {
  background: var(--surface-light);
  transform: translateY(-2px);
  color: var(--text-primary);
}

section {
  padding: 64px 0;
}

.section-title {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
  text-align: center;
}

.section-subtitle {
  color: var(--text-tertiary);
  text-align: center;
  margin-bottom: 48px;
  font-size: 1rem;
}

.features-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}

@media (min-width: 640px) {
  .features-grid {
    grid-template-columns: 1fr 1fr;
  }
}

.feature-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 28px;
  transition: all 0.3s ease;
}

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

.feature-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-l);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
  background: linear-gradient(
    135deg,
    rgba(79, 70, 229, 0.15),
    rgba(124, 58, 237, 0.15)
  );
}

.feature-icon svg {
  width: 24px;
  height: 24px;
  stroke: var(--primary-light);
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.feature-card h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.feature-card p {
  color: var(--text-secondary);
  font-size: 0.9375rem;
  line-height: 1.7;
}

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.faq-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-l);
  overflow: hidden;
  transition: border-color 0.2s ease;
}

.faq-item.open {
  border-color: var(--border-light);
}

.faq-question {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px;
  background: none;
  border: none;
  color: var(--text-primary);
  font-size: 1rem;
  font-weight: 600;
  font-family: var(--font);
  cursor: pointer;
  text-align: left;
  line-height: 1.5;
  gap: 16px;
}

.faq-question:hover {
  color: var(--primary-light);
}

.faq-chevron {
  width: 20px;
  height: 20px;
  stroke: var(--text-tertiary);
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  transition: transform 0.3s ease;
  flex-shrink: 0;
}

.faq-item.open .faq-chevron {
  transform: rotate(180deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease, padding 0.3s ease;
}

.faq-item.open .faq-answer {
  max-height: 300px;
}

.faq-answer-inner {
  padding: 0 24px 20px;
  color: var(--text-secondary);
  font-size: 0.9375rem;
  line-height: 1.8;
}

.contact-section {
  text-align: center;
}

.contact-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 40px;
  max-width: 480px;
  margin: 0 auto;
}

.contact-card p {
  color: var(--text-secondary);
  margin-bottom: 20px;
  font-size: 0.9375rem;
}

.contact-email {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--primary-light);
  font-weight: 600;
  font-size: 1rem;
  word-break: break-all;
}

.contact-email svg {
  width: 20px;
  height: 20px;
  stroke: var(--primary-light);
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  flex-shrink: 0;
}

footer {
  border-top: 1px solid var(--border);
  padding: 40px 0;
  margin-top: 40px;
}

.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}

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

.footer-links a {
  color: var(--text-tertiary);
  font-size: 0.875rem;
}

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

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

.legal-page {
  padding: 64px 0;
}

.legal-page h1 {
  font-size: 2rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 8px;
}

.legal-page .legal-updated {
  color: var(--text-tertiary);
  font-size: 0.875rem;
  margin-bottom: 40px;
}

.legal-page h2 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-top: 32px;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.legal-page p {
  color: var(--text-secondary);
  margin-bottom: 16px;
  line-height: 1.8;
}

.legal-page ul {
  color: var(--text-secondary);
  margin-bottom: 16px;
  padding-left: 24px;
  line-height: 1.8;
}

.legal-page li {
  margin-bottom: 4px;
}

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--text-tertiary);
  font-size: 0.875rem;
  margin-bottom: 32px;
}

.back-link svg {
  width: 16px;
  height: 16px;
  stroke: currentColor;
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

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

.placeholder-notice {
  background: rgba(79, 70, 229, 0.1);
  border: 1px solid rgba(79, 70, 229, 0.25);
  border-radius: var(--radius-l);
  padding: 24px;
  margin-bottom: 32px;
  color: var(--text-secondary);
  text-align: center;
  font-size: 0.9375rem;
}

@media (max-width: 639px) {
  .hero {
    padding: 56px 0 48px;
  }

  .hero h1 {
    font-size: 1.75rem;
  }

  .hero .subtitle {
    font-size: 1rem;
  }

  .section-title {
    font-size: 1.5rem;
  }

  .hero-actions {
    flex-direction: column;
    align-items: center;
  }

  .btn {
    width: 100%;
    max-width: 320px;
    justify-content: center;
  }

  section {
    padding: 48px 0;
  }
}