/* === 全体設定 === */
:root {
  --bg: #fafafa;
  --bg-alt: #ffffff;
  --text: #222;
  --accent: #2563eb;
  --accent-soft: #e0edff;
  --border: #e5e7eb;
}

body.theme-dark {
  --bg: #111827;
  --bg-alt: #020617;
  --text: #e5e7eb;
  --accent: #38bdf8;
  --accent-soft: #0f172a;
  --border: #1f2937;
}

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

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont,
    "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
}

/* === レイアウト === */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(10px);
  background: color-mix(in srgb, var(--bg-alt) 80%, transparent);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1.25rem;
  border-bottom: 1px solid var(--border);
}

.site-logo {
  font-weight: 700;
}

.site-nav {
  display: flex;
  gap: 1rem;
}

.site-nav a {
  text-decoration: none;
  font-size: 0.9rem;
  color: var(--text);
  opacity: 0.8;
}

.site-nav a:hover {
  opacity: 1;
}

main {
  max-width: 960px;
  margin: 0 auto;
  padding: 1.5rem 1rem 3rem;
}

/* === ボタン === */
.btn-main,
.btn-small {
  border: none;
  cursor: pointer;
  border-radius: 999px;
  font-size: 0.9rem;
}

.btn-main {
  padding: 0.8rem 1.6rem;
  background: var(--accent);
  color: #fff;
}

.btn-main:hover {
  opacity: 0.9;
}

.btn-small {
  padding: 0.4rem 0.9rem;
  background: var(--accent-soft);
  color: var(--accent);
}

/* === HERO === */
.hero {
  padding: 2.5rem 1rem 2rem;
  background: var(--bg-alt);
  border-radius: 1rem;
  border: 1px solid var(--border);
  margin-bottom: 2rem;
}

.hero h1 {
  margin-top: 0;
  margin-bottom: 0.4rem;
}

.hero p {
  margin-top: 0;
  margin-bottom: 1.4rem;
  line-height: 1.7;
}

/* === カードセクション === */
.cards-section {
  margin-bottom: 2.5rem;
}

.section-lead {
  margin-top: 0.3rem;
  margin-bottom: 1.2rem;
  font-size: 0.95rem;
  opacity: 0.9;
}

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

.card {
  background: var(--bg-alt);
  border-radius: 0.9rem;
  border: 1px solid var(--border);
  padding: 1rem;
  transition: transform 0.12s ease-out, box-shadow 0.12s ease-out;
}

.card h3 {
  margin-top: 0;
  margin-bottom: 0.4rem;
}

.card p {
  margin-top: 0;
  margin-bottom: 0.8rem;
  font-size: 0.9rem;
  line-height: 1.6;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 18px rgba(15, 23, 42, 0.12);
}

.tag {
  display: inline-block;
  padding: 0.15rem 0.6rem;
  font-size: 0.75rem;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
}

/* === About === */
.about-section {
  padding: 1.5rem 1rem;
  border-radius: 1rem;
  border: 1px dashed var(--border);
  background: color-mix(in srgb, var(--bg-alt) 80%, transparent);
}

/* === フッター === */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 1rem;
  text-align: center;
  font-size: 0.8rem;
  opacity: 0.7;
}

/* === スマホ調整 === */
@media (max-width: 600px) {
  .site-header {
    gap: 0.5rem;
  }

  .site-nav {
    display: none; /* 必要になったらハンバーガーに差し替え予定 */
  }

  .hero {
    padding: 2rem 1rem 1.7rem;
  }
}

/* === Reset CSS List Section === */
.reset-section {
  max-width: 960px;
  margin: 0 auto;
  margin-top: 3rem;
  padding: 1.5rem 1rem;
  border-radius: 1rem;
  border: 1px solid var(--border);
  background: var(--bg-alt);
}

.reset-list {
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}

.reset-item {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 0.8rem;
  padding: 1rem;
}

.reset-item h3 {
  margin: 0 0 0.4rem;
  font-size: 1rem;
}

.reset-item p {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.6;
}