:root {
  color-scheme: light;
  font-family: "Yu Gothic UI", "Hiragino Kaku Gothic ProN", "Noto Sans JP", sans-serif;
  background: #f8fafc;
  color: #111827;
  --bg: #f8fafc;
  --surface: #ffffff;
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --text: #111827;
  --muted: #6b7280;
  --border: #e5e7eb;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
}

body {
  background: radial-gradient(circle at top, rgba(56, 189, 248, 0.12), transparent 35%),
    linear-gradient(180deg, rgba(248, 250, 252, 1), rgba(241, 245, 249, 1));
}

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

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

.container {
  width: min(1120px, calc(100% - 2rem));
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(229, 231, 235, 0.8);
}

.header-inner,
.footer-inner,
.hero-content,
.download-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}

.header-inner {
  padding: 1rem 0;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.15rem;
  font-weight: 700;
}

.brand-icon {
  width: 42px;
  height: 42px;
  border-radius: 12px;
}

.nav-links {
  display: flex;
  gap: 1.25rem;
  flex-wrap: wrap;
}

.nav-links a {
  color: var(--text);
  font-weight: 600;
}

.hero {
  padding: 5rem 0 3rem;
}

.hero-content {
  align-items: center;
}

.hero-copy,
.section p,
.note {
  color: var(--muted);
  line-height: 1.8;
}

.eyebrow {
  margin: 0 0 1rem;
  font-size: 0.95rem;
  font-weight: 700;
  color: #2563eb;
  text-transform: uppercase;
  letter-spacing: 0.14em;
}

.hero h1 {
  margin: 0;
  font-size: clamp(2.5rem, 4vw, 4rem);
  line-height: 1.05;
}

.hero-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
  margin-top: 2rem;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 1rem 1.6rem;
  border-radius: 999px;
  font-weight: 700;
  transition: transform 160ms ease, box-shadow 160ms ease, background-color 160ms ease;
}

.button:hover {
  transform: translateY(-1px);
}

.primary {
  background: var(--primary);
  color: #ffffff;
}

.primary:hover {
  background: var(--primary-dark);
}

.secondary {
  background: rgba(37, 99, 235, 0.1);
  color: var(--primary);
}

.section {
  padding: 4rem 0;
}

.section h2 {
  margin-bottom: 1.75rem;
  font-size: 2rem;
}

.features .feature-grid,
.courses .course-grid {
  display: grid;
  gap: 1.25rem;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
}

.feature-card,
.course-card,
.contact-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 24px;
  padding: 1.75rem;
  box-shadow: 0 18px 60px rgba(15, 23, 42, 0.06);
}

.feature-card h3,
.course-card h3 {
  margin-top: 0;
}

.download-inner {
  align-items: flex-start;
  padding: 2rem 0;
}

.download-preview {
  flex: 1;
  display: flex;
  justify-content: center;
}

.mobile-card {
  width: min(320px, 100%);
  border-radius: 32px;
  padding: 2rem;
  background: linear-gradient(180deg, #ffffff 0%, #f8fafc 100%);
  border: 1px solid rgba(226, 232, 240, 0.9);
  text-align: center;
  box-shadow: 0 24px 70px rgba(15, 23, 42, 0.08);
}

.mobile-card span {
  display: inline-block;
  margin-bottom: 1rem;
  font-weight: 700;
  color: var(--primary);
}

.mobile-card img {
  width: 96px;
  margin: 0 auto 1rem;
}

.mobile-card p {
  margin: 0;
  font-size: 1rem;
  color: var(--text);
}

.install-steps {
  padding-left: 1.35rem;
  margin: 1.5rem 0;
}

.install-steps li {
  margin-bottom: 0.75rem;
}

.note {
  margin-top: 1rem;
  font-size: 0.95rem;
}

.contact-card {
  max-width: 720px;
}

.contact-email a {
  color: var(--primary);
  font-weight: 700;
}

.site-footer {
  padding: 1.25rem 0 2rem;
  color: var(--muted);
}

.footer-inner {
  justify-content: space-between;
  gap: 1rem;
}

@media (max-width: 900px) {
  .header-inner,
  .hero-content,
  .download-inner,
  .footer-inner {
    flex-direction: column;
    align-items: stretch;
  }

  .hero-image,
  .download-preview {
    order: -1;
  }
}

@media (max-width: 640px) {
  .nav-links {
    justify-content: center;
  }

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

  .mobile-card {
    padding: 1.5rem;
  }
}