/* 共通スタイル */
:root {
  --bg: #f5f7fb;
  --card: #ffffff;
  --primary: #1e40af;
  /* 深めのインディゴで落ち着いた印象 */
  --primary-dark: #172554;
  --muted: #6b7280;
  --text: #0f1724;
  --accent: #ff7a59;
  /* 温かみのあるアクセント色 */
  --shadow: rgba(15, 23, 42, 0.08);
}

body {
  margin: 0;
  font-family: "Noto Sans JP", "m-plus-1mn", system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-weight: 500;
  /* 可読性向上のため太めに設定 */
  font-size: 16px;
  font-style: normal;
  background-color: var(--bg);
  color: var(--text);
  padding-top: 60px;
  /* ヘッダー分の余白 */
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* メインコンテンツ */
.content {
  padding: 24px;
  max-width: 1100px;
  margin: auto;
  padding-bottom: 0px;
  margin-bottom: 32px;
  background: transparent;
}

.content h2 {
  font-weight: 700;
  margin: 0px;
  font-size: 1.4rem;
  color: var(--text);
}

/* ヘッダー */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  background: linear-gradient(45deg, #444, #222);
  /* 元のダークグラデに戻す */
  color: white;
  z-index: 1000;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
  transition: all 0.3s ease;
}

.header-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 24px;
}

footer {
  position: relative;
  bottom: 0;
  width: 100%;
  background: #333;
}

.footer-text {
  color: #fff;
  text-align: center;
  margin: 0px 6px;
  font-size: 0.85rem;
}

.logo {
  font-size: 1.5em;
  font-weight: bold;
  cursor: pointer;
}

.nav-menu {
  display: flex;
}

.nav-menu ul {
  display: flex;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-menu ul li {
  margin: 0 15px;
}

.nav-menu ul li a {
  color: white;
  text-decoration: none;
  font-size: 1rem;
  font-weight: 600;
  padding: 6px 8px;
  border-radius: 6px;
  transition: background 0.18s ease, transform 0.18s ease;
}

.nav-menu ul li a:hover,
.nav-menu ul li a:focus-visible {
  background: rgba(255, 255, 255, 0.06);
  transform: translateY(-1px);
}

/* フォーカスの視認性向上 */
a:focus,
button:focus,
.menu-toggle:focus {
  outline: 3px solid rgba(43, 124, 255, 0.18);
  outline-offset: 2px;
}

/* ハンバーガーメニュー */
.menu-toggle {
  display: none;
  background: none;
  border: none;
  color: white;
  font-size: 1.6em;
  cursor: pointer;
}

.video-link {
  width: 95%;
  margin: auto;
}

/* レスポンシブ対応 */
@media (max-width: 780px) {
  .video-link {
    width: 100%;
  }

  .nav-menu {
    display: none;
    /* 初期は非表示 */
    position: absolute;
    top: 60px;
    left: 0;
    width: 100%;
    background: #333;
    flex-direction: column;
    text-align: center;
  }

  .nav-menu ul {
    flex-direction: column;
  }

  .nav-menu ul li {
    margin: 10px 0;
  }

  .menu-toggle {
    display: block;
    /* ハンバーガーメニュー表示 */
  }

  .nav-menu.active {
    display: flex;
    /* ハンバーガーメニュー展開時 */
  }

  .content {
    padding: 20px 0;
  }
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 10px;
}

.video-card {
  background: var(--card);
  border: 1px solid rgba(15, 23, 42, 0.06);
  border-radius: 10px;
  overflow: hidden;
  text-align: center;
  transition: transform 0.22s ease, box-shadow 0.22s ease;
}

.video-card img {
  width: 100%;
  height: 110px;
  object-fit: cover;
  display: block;
}

.video-card h3 {
  padding: 10px;
}

.video-card p {
  padding: 6px 8px 8px 8px;
  margin: 0;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text);
}

.video-card a {
  text-decoration: none;
  color: inherit;
}

.video-card a:hover p {
  color: #0f1724;
}

/* ホバーエフェクト */
.video-card:hover {
  transform: scale(1.03);
  box-shadow: 0 10px 24px var(--shadow);
}

section {
  padding: 12px 0;
  padding-bottom: 0;
}

/* ヒーローセクション */
.hero {
  margin: 8px 0 20px 0;
}

.hero-inner {
  display: grid;
  grid-template-columns: 1fr 280px;
  gap: 20px;
  align-items: center;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.95), rgba(255, 255, 255, 0.9));
  border-radius: 14px;
  padding: 20px 24px;
  box-shadow: 0 8px 24px rgba(15, 23, 42, 0.06);
}

.hero-title {
  font-size: 1.5rem;
  margin: 0 0 6px 0;
  font-weight: 800;
  letter-spacing: -0.02em;
}

.hero-sub {
  margin: 0 0 14px 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.hero-ctas {
  display: flex;
  gap: 12px;
  align-items: center;
}

.cta-button {
  display: inline-block;
  padding: 10px 14px;
  border-radius: 10px;
  text-decoration: none;
  background: transparent;
  color: #3b82f6;
  border: 1px solid rgba(59, 130, 246, 0.3);
  font-weight: 700;
  transition: transform 0.14s ease, box-shadow 0.14s ease, background 0.14s ease, color 0.14s ease;
}

.cta-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(59, 130, 246, 0.2);
  color: #1e40af;
  border-color: rgba(59, 130, 246, 0.5);
}

.cta-button.primary {
  background: #3b82f6;
  color: #fff;
  border: none;
  box-shadow: 0 10px 24px rgba(59, 130, 246, 0.3);
}

.cta-button.primary:hover {
  background: #1e40af;
}

/* リンクの基本スタイル */
a {
  color: var(--primary);
  text-decoration: none;
}

a:hover,
a:focus {
  color: var(--primary-dark);
  text-decoration: underline;
}

.hero-media {
  position: relative;
  display: block;
  text-decoration: none;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.hero-media:hover,
.hero-media:focus {
  transform: scale(1.05);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.2);
  text-decoration: none;
}

.hero-media::after {
  content: "▶ YouTubeを見る";
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: rgba(0, 0, 0, 0.7);
  color: white;
  padding: 10px 16px;
  border-radius: 8px;
  font-weight: 700;
  font-size: 16px;
  opacity: 0;
  transition: opacity 0.3s ease;
  pointer-events: none;
  white-space: nowrap;
}

.hero-media:hover::after {
  opacity: 1;
}

.hero-media img {
  width: 100%;
  height: auto;
  border-radius: 10px;
  display: block;
}

@media (max-width: 780px) {
  .hero-inner {
    grid-template-columns: 1fr;
    text-align: center;
    padding: 16px;
    gap: 12px;
  }

  .hero-title {
    font-size: 1.3rem;
    margin: 0 0 6px 0;
  }

  .hero-sub {
    font-size: 0.9rem;
    margin: 0 0 12px 0;
  }

  .hero-ctas {
    justify-content: center;
    gap: 8px;
    flex-wrap: wrap;
  }

  .cta-button {
    padding: 8px 12px;
    font-size: 0.9rem;
  }

  .hero-media {
    order: -1;
    max-width: 280px;
    margin: 0 auto;
  }
}

/* スクリーンリーダー向け非表示（アクセシビリティ用） */
.sr-only {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}