/* ai-cube.jp — minimal style */

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

:root {
  --text: #1a1a1a;
  --muted: #767676;
  --line: #e8e8e8;
  --bg: #ffffff;
  --soft-bg: #fafafa;
}

html {
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Helvetica Neue",
    "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Yu Gothic", "Meiryo",
    "Noto Sans JP", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.8;
  letter-spacing: 0.02em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a:hover {
  opacity: 0.55;
}

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 28px;
}

/* ── Header ─────────────────────────── */
header {
  border-bottom: 1px solid var(--line);
  padding: 22px 0;
}

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

.logo {
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: 0.08em;
}

nav a {
  color: var(--muted);
  font-size: 0.85rem;
  margin-left: 22px;
  letter-spacing: 0.04em;
}

nav a:hover {
  color: var(--text);
  opacity: 1;
}

/* ── Main ───────────────────────────── */
main {
  padding: 96px 0 120px;
}

h1 {
  font-size: 1.6rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  margin-bottom: 40px;
}

h2 {
  font-size: 1rem;
  font-weight: 600;
  margin: 36px 0 10px;
  letter-spacing: 0.04em;
}

p {
  margin-bottom: 18px;
  color: #2a2a2a;
  font-size: 0.95rem;
}

ul,
ol {
  padding-left: 1.4em;
  margin-bottom: 18px;
}

li {
  margin-bottom: 6px;
  font-size: 0.95rem;
  color: #2a2a2a;
}

/* ── Hero ───────────────────────────── */
.hero {
  text-align: center;
  margin-bottom: 96px;
  padding: 24px 0 8px;
}

.hero .equation {
  font-size: 1.4rem;
  letter-spacing: 0.2em;
  font-weight: 400;
  margin-bottom: 18px;
}

.hero .tagline {
  color: var(--muted);
  font-size: 0.9rem;
  letter-spacing: 0.06em;
  line-height: 1.9;
}

/* ── Info table ─────────────────────── */
.info-table {
  border-top: 1px solid var(--line);
  margin-top: 40px;
}

.info-table dl {
  display: grid;
  grid-template-columns: 140px 1fr;
}

.info-table dt,
.info-table dd {
  padding: 18px 0;
  border-bottom: 1px solid var(--line);
  font-size: 0.92rem;
}

.info-table dt {
  color: var(--muted);
  font-weight: 400;
}

.info-table dd {
  color: var(--text);
}

/* ── Contact block ──────────────────── */
.contact-block {
  background: var(--soft-bg);
  padding: 32px 28px;
  border-radius: 4px;
  margin: 32px 0;
  text-align: center;
}

.contact-block .email {
  font-size: 1.1rem;
  letter-spacing: 0.04em;
  margin-top: 8px;
  display: inline-block;
}

.contact-block .label {
  color: var(--muted);
  font-size: 0.85rem;
  letter-spacing: 0.06em;
}

/* ── Footer ─────────────────────────── */
footer {
  border-top: 1px solid var(--line);
  padding: 32px 0;
  color: var(--muted);
  font-size: 0.8rem;
  text-align: center;
  letter-spacing: 0.04em;
}

footer a {
  color: var(--muted);
  margin: 0 10px;
}

/* ── Responsive ─────────────────────── */
@media (max-width: 600px) {
  main {
    padding: 64px 0 80px;
  }

  h1 {
    font-size: 1.3rem;
  }

  .hero .equation {
    font-size: 1.2rem;
    letter-spacing: 0.15em;
  }

  .info-table dl {
    grid-template-columns: 100px 1fr;
  }

  nav a {
    margin-left: 14px;
    font-size: 0.8rem;
  }

  .contact-block {
    padding: 24px 20px;
  }

  .contact-block .email {
    font-size: 1rem;
  }
}