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

:root {
  --bg-gradient: linear-gradient(180deg, #1b263b 0%, #0d1b2a 100%);
  
  /* カード周りのカラー定義（ダークテーマに合わせた高コントラスト調整） */
  --card-bg: #1e293b;
  --card-hover-bg: #24334a;
  --card-border: rgba(255, 255, 255, 0.1);
  
  --text-main: #f8fafc;
  --text-sub: #94a3b8;
  --text-muted: #64748b;

  --accent-primary: #38bdf8;
  --accent-secondary: #818cf8;
  --link-color: #60a5fa;

  --shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
  --radius: 16px;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: var(--bg-gradient);
  background-attachment: fixed;
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
  min-height: 100vh;
}

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

a:hover {
  color: #93c5fd;
  text-decoration: underline;
}

.container {
  width: min(1120px, calc(100% - 32px));
  margin: auto;
}

/* Header & Hero */
header {
  padding: 80px 0 60px;
}

.hero {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 40px;
  align-items: center;
}

.tag {
  display: inline-flex;
  align-items: center;
  padding: 6px 14px;
  border-radius: 999px;
  background: rgba(56, 189, 248, 0.1);
  border: 1px solid rgba(56, 189, 248, 0.2);
  color: var(--accent-primary);
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 20px;
}

h1 {
  font-size: clamp(2.2rem, 5vw, 3.2rem);
  line-height: 1.2;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 20px;
  background: linear-gradient(135deg, #ffffff 0%, #cbd5e1 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-text {
  color: var(--text-sub);
  font-size: 1.05rem;
  margin-bottom: 28px;
}

.buttons {
  display: flex;
  gap: 16px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 24px;
  border-radius: 12px;
  font-weight: 600;
  font-size: 0.95rem;
  transition: all 0.2s ease;
}

.btn.primary {
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  color: #fff;
  box-shadow: 0 4px 20px rgba(56, 189, 248, 0.3);
}

.btn.primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(56, 189, 248, 0.4);
  text-decoration: none;
}

.btn.primary-outline {
  border: 1px solid rgba(56, 189, 248, 0.4);
  background: rgba(56, 189, 248, 0.05);
  color: var(--accent-primary);
}

.btn.primary-outline:hover {
  background: rgba(56, 189, 248, 0.15);
  text-decoration: none;
}

.hero-card {
  background: rgba(30, 41, 59, 0.7);
  border: 1px solid var(--card-border);
  backdrop-filter: blur(12px);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow);
}

.hero-card h2 {
  font-size: 1.4rem;
  margin-bottom: 12px;
}

/* Main Content */
main {
  padding-bottom: 80px;
}

section {
  margin-top: 60px;
}

.section-title {
  font-size: 1.8rem;
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.section-sub {
  color: var(--text-sub);
  max-width: 800px;
  margin-bottom: 32px;
  font-size: 1rem;
}

/* Card Grid */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  padding: 24px;
  display: flex;
  flex-direction: column;
  transition: transform 0.2s ease, border-color 0.2s ease, background 0.2s ease;
  box-shadow: var(--shadow);
}

.card:hover {
  transform: translateY(-4px);
  background: var(--card-hover-bg);
  border-color: rgba(56, 189, 248, 0.3);
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
}

.card-header h3 {
  font-size: 1.3rem;
  margin: 0;
}

.card-header h3 a {
  color: var(--text-main);
  text-decoration: none;
}

.card-header h3 a:hover {
  color: var(--accent-primary);
}

/* Badge Styles */
.badge {
  padding: 4px 10px;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.badge.official {
  background: rgba(56, 189, 248, 0.15);
  color: #38bdf8;
  border: 1px solid rgba(56, 189, 248, 0.3);
}

.badge.community {
  background: rgba(168, 85, 247, 0.15);
  color: #c084fc;
  border: 1px solid rgba(168, 85, 247, 0.3);
}

.badge.sandbox {
  background: rgba(251, 146, 60, 0.15);
  color: #fb923c;
  border: 1px solid rgba(251, 146, 60, 0.3);
}

.card-desc {
  color: var(--text-sub);
  font-size: 0.92rem;
  margin-bottom: 16px;
  flex-grow: 0;
}

/* Link Lists inside Cards */
.link-list {
  list-style: none;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  padding-top: 12px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.link-list li {
  font-size: 0.9rem;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  align-items: baseline;
}

.link-list li a {
  font-weight: 500;
}

.link-list li .meta {
  color: var(--text-muted);
  font-size: 0.82rem;
}

.sub-section {
  margin-top: 16px;
  padding-top: 12px;
  border-top: 1px dashed rgba(255, 255, 255, 0.1);
}

.sub-title {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 8px;
}

/* Footer */
footer {
  margin-top: 80px;
  padding-top: 24px;
  border-top: 1px solid var(--card-border);
  color: var(--text-muted);
  font-size: 0.875rem;
  text-align: center;
}

/* Responsive */
@media (max-width: 900px) {
  header {
    padding: 40px 0 30px;
  }

  .hero {
    grid-template-columns: 1fr;
    gap: 32px;
  }
}

@media (max-width: 600px) {
  .grid {
    grid-template-columns: 1fr;
  }

  .buttons {
    flex-direction: column;
  }

  .btn {
    width: 100%;
  }
}