:root {
  --bg: #fafaf9;
  --fg: #1c1917;
  --muted: #57534e;
  --line: #e7e5e4;
  --accent: #0f766e;
  --max: 38rem;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", "PingFang SC",
    "Hiragino Sans", "Noto Sans SC", "Noto Sans JP", "Microsoft YaHei", sans-serif;
  color: var(--fg);
  background: var(--bg);
  line-height: 1.65;
}

a { color: inherit; }
a:hover { color: var(--accent); }

.site-header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem 1.25rem;
  max-width: 64rem;
  margin: 0 auto;
  padding: 1.1rem 1.5rem;
}
.logo {
  display: inline-flex;
  align-items: baseline;
  gap: 0.45rem;
  font-weight: 650;
  text-decoration: none;
  letter-spacing: 0.01em;
}
.logo-sub {
  font-weight: 500;
  color: var(--muted);
  font-size: 0.95rem;
}
nav {
  display: flex;
  gap: 1.1rem;
  font-size: 0.95rem;
  margin-left: auto;
}
nav a { text-decoration: none; color: var(--muted); }
nav a:hover { color: var(--fg); }

.lang {
  display: inline-flex;
  border: 1px solid var(--line);
  border-radius: 999px;
  overflow: hidden;
  background: #fff;
}
.lang button {
  appearance: none;
  border: 0;
  background: transparent;
  color: var(--muted);
  font: inherit;
  font-size: 0.8rem;
  padding: 0.35rem 0.65rem;
  cursor: pointer;
}
.lang button[aria-pressed="true"] {
  background: var(--fg);
  color: #fff;
}
.lang button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

main { max-width: 64rem; margin: 0 auto; padding: 0 1.5rem 4rem; }

.hero {
  padding: 4rem 0 3.25rem;
  max-width: var(--max);
}
.eyebrow {
  margin: 0 0 0.75rem;
  color: var(--accent);
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.04em;
}
.hero h1 {
  font-size: clamp(2rem, 4.2vw, 2.7rem);
  line-height: 1.2;
  font-weight: 650;
  letter-spacing: -0.02em;
  margin: 0 0 1rem;
}
.lede {
  color: var(--muted);
  font-size: 1.08rem;
  margin: 0 0 1.75rem;
}
.btn {
  display: inline-block;
  background: var(--accent);
  color: #fff !important;
  text-decoration: none;
  padding: 0.7rem 1.15rem;
  border-radius: 0.5rem;
  font-weight: 550;
}
.btn:hover { filter: brightness(1.06); }

.section { padding: 2.4rem 0; border-top: 1px solid var(--line); }
.section h2 {
  font-size: 1.2rem;
  margin: 0 0 1rem;
  font-weight: 650;
}
.prose {
  max-width: var(--max);
  margin: 0;
  color: var(--muted);
}
.section.muted { color: var(--muted); }
.section.muted h2 { color: var(--fg); }

.cards {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 1.15rem;
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
}
.cards li {
  padding: 1.1rem 1.15rem;
  border: 1px solid var(--line);
  border-radius: 0.75rem;
  background: #fff;
}
.cards h3 {
  margin: 0 0 0.4rem;
  font-size: 1rem;
  font-weight: 650;
}
.cards p {
  margin: 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.site-footer {
  max-width: 64rem;
  margin: 0 auto;
  padding: 1.4rem 1.5rem 2rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.875rem;
}

@media (max-width: 640px) {
  nav { order: 3; width: 100%; margin-left: 0; }
  .lang { margin-left: auto; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

/* icons */
.icon { width: 1.5rem; height: 1.5rem; flex: none; }
.logo { display: inline-flex; align-items: center; gap: .5rem; }
.logo-mark { width: 1.25rem; height: 1.25rem; }
.card-icon { display: inline-flex; color: inherit; opacity: .75; margin-bottom: .75rem; }
.card-icon .icon { width: 1.75rem; height: 1.75rem; }
.lang { align-items: center; }
.lang-icon { width: 1rem; height: 1rem; opacity: .6; margin: 0 .2rem 0 .6rem; }
.mail { display: inline-flex; align-items: center; gap: .4rem; }
.mail .icon { width: 1.1rem; height: 1.1rem; }
.card-icon.app { opacity: 1; }
.app-icon { width: 52px; height: 52px; border-radius: 12px; border: 1px solid rgba(0,0,0,.08); display: block; }
@media (max-width: 480px) { .app-icon { width: 48px; height: 48px; border-radius: 11px; } }