::root {
  --bg: #050816;
  --fg: #f5f6ff;
  --accent: #ff6aa8;      /* ピンク（会話の温度） */
  --accent-sub: #5fd4ff;  /* シアン（画面・通話の光） */
  --card-bg: #0b1020;
  --border: #262b40;
  --radius: 14px;
  --shadow-soft: 0 18px 40px rgba(0, 0, 0, 0.7);
}

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

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background:
    radial-gradient(circle at top left, #2a2746 0, transparent 45%),
    radial-gradient(circle at top right, #163a5f 0, transparent 55%),
    radial-gradient(circle at bottom, #101322 0, #050816 60%);
  color: var(--fg);
  line-height: 1.7;
}

/* ヘッダー */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(5, 8, 22, 0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 0.6rem 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.site-brand {
  display: flex;
  flex-direction: column;
}

.site-title {
  font-weight: 700;
  letter-spacing: 0.04em;
  text-decoration: none;
  color: var(--fg);
}

.site-subtitle {
  font-size: 0.7rem;
  opacity: 0.7;
}

.site-nav ul {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.site-nav a {
  text-decoration: none;
  font-size: 0.85rem;
  padding: 0.3rem 0.7rem;
  border-radius: 999px;
  color: var(--fg);
  border: 1px solid transparent;
}

.site-nav a:hover {
  background: rgba(255, 255, 255, 0.04);
  border-color: rgba(95, 212, 255, 0.35);
}

/* メイン */
.page-main {
  max-width: 960px;
  margin: 1.6rem auto 2.6rem;
  padding: 0 1rem;
}

.section {
  margin-bottom: 2rem;
}

.section-title {
  margin: 0 0 0.8rem;
  font-size: 1.3rem;
}

/* hero */
.hero {
  background:
    linear-gradient(135deg, rgba(255,106,168,0.15), rgba(95,212,255,0.08)),
    radial-gradient(circle at top, #222a56 0, #0a0f23 52%, #050816 100%);
  border-radius: 20px;
  box-shadow: var(--shadow-soft);
  padding: 1.8rem 1.5rem 2.1rem;
  margin-bottom: 2rem;
  border: 1px solid rgba(95, 212, 255, 0.16);
}

.hero-label {
  display: inline-block;
  font-size: 0.75rem;
  padding: 0.2rem 0.7rem;
  border-radius: 999px;
  background: rgba(5, 8, 22, 0.75);
  border: 1px solid rgba(255,106,168,0.5);
  color: var(--accent);
  margin-bottom: 0.6rem;
}

.hero-title-jp {
  margin: 0.4rem 0;
  font-size: 1.4rem;
  line-height: 1.6;
}

.hero-title-en {
  margin: 0.1rem 0 0.8rem;
  font-size: 0.85rem;
  opacity: 0.7;
}

.hero-lead {
  margin: 0 0 1.2rem;
  font-size: 0.95rem;
  opacity: 0.95;
}

.hero-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
}

/* button */
.btn {
  display: inline-block;
  text-decoration: none;
  border-radius: 999px;
  padding: 0.5rem 1.2rem;
  font-size: 0.9rem;
  border: 1px solid transparent;
  cursor: pointer;
}

.btn.primary {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 10px 22px rgba(255,106,168,0.4);
}

.btn.outline {
  background: transparent;
  color: var(--accent-sub);
  border-color: var(--accent-sub);
}

.btn.small {
  padding: 0.4rem 0.9rem;
  font-size: 0.8rem;
}

/* card */
.card-grid {
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
}

.card {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow-soft);
  padding: 1rem 1.2rem 1.3rem;
  border: 1px solid rgba(38, 43, 64, 0.9);
}

.card h3 {
  margin: 0 0 0.4rem;
  font-size: 1.05rem;
}

.card p {
  margin: 0.3rem 0 0.8rem;
  font-size: 0.9rem;
  opacity: 0.95;
}

.card-link {
  display: inline-block;
  font-size: 0.85rem;
  text-decoration: none;
  color: var(--accent-sub);
}

.card-link::after {
  content: " →";
}

/* Box */
.text-box {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow-soft);
  padding: 1.1rem 1.3rem 1.3rem;
  font-size: 0.95rem;
  border: 1px solid rgba(38, 43, 64, 0.9);
}

/* footer */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 0.8rem 1rem 1rem;
  text-align: center;
  font-size: 0.8rem;
  color: rgba(214, 218, 255, 0.7);
}

/* スマホ */
@media (max-width: 640px) {
  .header-inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .hero {
    padding: 1.4rem 1.1rem 1.7rem;
  }

  .page-main {
    margin-top: 1.2rem;
  }
}