/* ===== リセット & ベース ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --color-primary: #0ea5e9;
  --color-primary-dark: #0369a1;
  --color-text: #1f2937;
  --color-muted: #6b7280;
  --color-bg-light: #f9fafb;
  --color-white: #ffffff;
  --radius: 12px;
  --transition: 0.3s ease;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Segoe UI', 'Hiragino Sans', sans-serif;
  color: var(--color-text);
  line-height: 1.7;
}

/* ===== ナビゲーション ===== */
header {
  position: fixed;
  top: 0;
  width: 100%;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid #e5e7eb;
  z-index: 100;
}

nav {
  max-width: 1100px;
  margin: 0 auto;
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--color-primary);
}

nav ul {
  list-style: none;
  display: flex;
  gap: 2rem;
}

nav a {
  text-decoration: none;
  color: var(--color-text);
  font-weight: 500;
  transition: color var(--transition);
}

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

/* ===== ヒーロー ===== */
.hero {
  min-height: 100vh;
  background:
    linear-gradient(to bottom, rgba(0,0,0,0.45) 0%, rgba(0,0,0,0.25) 60%, rgba(0,0,0,0.55) 100%),
    url('https://images.unsplash.com/photo-1506929562872-bb421503ef21?w=1600&auto=format&fit=crop') center/cover no-repeat;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  color: var(--color-white);
  padding: 2rem;
}

.hero-content h1 {
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: 800;
  margin-bottom: 1rem;
  text-shadow: 0 2px 12px rgba(0,0,0,0.5);
  letter-spacing: 0.04em;
}

.hero-content p {
  font-size: clamp(1rem, 2.5vw, 1.4rem);
  opacity: 0.9;
  margin-bottom: 2rem;
  text-shadow: 0 1px 6px rgba(0,0,0,0.4);
}

/* ===== ボタン ===== */
.btn {
  display: inline-block;
  padding: 0.8rem 2rem;
  background: var(--color-white);
  color: var(--color-primary);
  font-weight: 600;
  border-radius: 50px;
  text-decoration: none;
  transition: transform var(--transition), box-shadow var(--transition);
  box-shadow: 0 4px 15px rgba(0,0,0,0.15);
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(0,0,0,0.2);
}

/* ===== セクション共通 ===== */
.section {
  padding: 5rem 2rem;
}

.bg-light {
  background: var(--color-bg-light);
}

.container {
  max-width: 1100px;
  margin: 0 auto;
}

.section h2 {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 1.2rem;
  position: relative;
  display: inline-block;
}

.section h2::after {
  content: '';
  position: absolute;
  bottom: -6px;
  left: 0;
  width: 50%;
  height: 4px;
  background: var(--color-primary);
  border-radius: 2px;
}

.section p {
  color: var(--color-muted);
  font-size: 1.05rem;
  margin-top: 1rem;
}

/* ===== カードグリッド ===== */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

.card {
  background: var(--color-white);
  border-radius: var(--radius);
  padding: 1.8rem;
  box-shadow: 0 2px 12px rgba(0,0,0,0.07);
  transition: transform var(--transition), box-shadow var(--transition);
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 25px rgba(0,0,0,0.12);
}

.card h3 {
  font-size: 1.2rem;
  margin-bottom: 0.6rem;
  color: var(--color-primary);
}

/* ===== Contact ===== */
#contact .btn {
  background: var(--color-primary);
  color: var(--color-white);
  margin-top: 1.5rem;
}

#contact .btn:hover {
  background: var(--color-primary-dark);
}

/* ===== フッター ===== */
footer {
  background: var(--color-text);
  color: rgba(255,255,255,0.6);
  text-align: center;
  padding: 1.5rem;
  font-size: 0.9rem;
}

/* ===== レスポンシブ ===== */
@media (max-width: 640px) {
  nav ul {
    gap: 1rem;
    font-size: 0.9rem;
  }
}