:root {
      --brand-50:#f0fdf4; /* green-50 */
      --brand-100:#dcfce7;
      --brand-200:#bbf7d0;
      --brand-300:#86efac;
      --brand-400:#4ade80;
      --brand-500:#22c55e; /* primary */
      --brand-600:#16a34a;
      --brand-700:#15803d;
      --ink-900:#0b1b13;
      --ink-800:#11271a;
      --ink-700:#1b3a27;
      --ink-600:#355b45;
      --muted:#6b7280;
      --card:#ffffff;
      --bg:#f7fcf9;
      --ring: 0 0 0 3px rgba(34,197,94,.25);
      --radius: 16px;
      --shadow: 0 8px 24px rgba(16, 185, 129, .12), 0 2px 8px rgba(0,0,0,.06);
    }

    @media (prefers-color-scheme: dark) {
      :root{
        --card:#0e1511;
        --bg:#08110c;
        --ink-900:#e7f6ec;
        --ink-800:#d2eadb;
        --muted:#9aa7a1;
        --shadow: 0 6px 20px rgba(0,0,0,.45);
      }
    }

    *{ box-sizing: border-box; }
    html, body { margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, Segoe UI, Roboto, Noto Sans JP, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
      line-height: 1.65; color: var(--ink-900); background: radial-gradient(1200px 600px at 10% -10%, var(--brand-50), transparent), var(--bg);
    }

    .container { width: min(1100px, 100% - 32px); margin-inline: auto; }

    header {
      position: sticky; top: 0; z-index: 50; backdrop-filter: saturate(140%) blur(8px);
      background: color-mix(in srgb, var(--bg) 75%, transparent);
      border-bottom: 1px solid color-mix(in srgb, var(--brand-500) 20%, transparent);
    }
    .nav { display: flex; align-items: center; justify-content: space-between; padding: 12px 0; }
    .brand { display:flex; gap:12px; align-items:center; font-weight:700; }
    .logo {
      width:40px; height:40px; border-radius: 12px; background: linear-gradient(135deg, var(--brand-500), var(--brand-700));
      box-shadow: inset 0 0 0 2px rgba(255,255,255,.25), 0 6px 14px rgba(34,197,94,.35);
      position: relative;
    }
    .logo::after{ content:"邪"; position:absolute; inset:0; display:grid; place-items:center; color:white; font-weight:900; }
    .nav a { color: var(--ink-900); text-decoration: none; font-size: 14px; padding: 8px 12px; border-radius: 999px; }
    .nav a:hover { background: var(--brand-100); }

    .hero { padding: 40px 0 28px; }
    .hero-grid { display: grid; grid-template-columns: 1.05fr .95fr; gap: 28px; align-items: center; }
    @media (max-width: 920px){ .hero-grid{ grid-template-columns: 1fr; } }

    .badge { display:inline-flex; align-items:center; gap:8px; padding:6px 10px; border-radius:999px; font-weight:600; font-size:12px;
      background: linear-gradient(180deg, var(--brand-100), #fff); border:1px solid var(--brand-200); color: var(--ink-700);
    }

    h1 { font-size: clamp(26px, 3.4vw + .5rem, 42px); line-height:1.2; margin: 10px 0 12px; letter-spacing: .01em; }
    .lead { color: var(--ink-700); font-size: clamp(15px, 1.2vw + .6rem, 18px); }

    .cta { display:flex; gap:12px; margin-top: 18px; flex-wrap: wrap; }
    .btn { appearance: none; border: 0; border-radius: 999px; padding: 12px 18px; font-weight: 700; cursor: pointer; }
    .btn.primary{ background: linear-gradient(180deg, var(--brand-400), var(--brand-600)); color:white; box-shadow: 0 6px 18px rgba(34,197,94,.35); }
    .btn.primary:focus-visible{ outline: none; box-shadow: var(--ring); }
    .btn.ghost{ background: transparent; border: 1px solid var(--brand-300); color: var(--brand-700); }

    .panel { background: var(--card); border-radius: var(--radius); box-shadow: var(--shadow); padding: 18px; }

    .kicker { font-size: 12px; letter-spacing:.12em; text-transform: uppercase; color: var(--muted); font-weight: 700; }

    /* videos */
    .videos{ padding: 24px 0 60px; }
    .videos h2{ margin: 0 0 8px; }
    .videos .sub{ color: var(--ink-700); margin: 0 0 16px; }

    .grid{ display:grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 16px; }

    .card{ background: var(--card); border-radius: 14px; box-shadow: var(--shadow); overflow: clip; display:flex; flex-direction: column; }
    .thumb{ position:relative; aspect-ratio: 16 / 9; background: #d1fae5; display:block; }
    .thumb img{ width:100%; height:100%; object-fit:cover; display:block; }
    .play{ position:absolute; inset:auto 12px 12px auto; display:inline-flex; align-items:center; gap:8px; font-weight:700; padding:8px 12px; border-radius:999px; background: color-mix(in srgb, var(--brand-500) 85%, black 0%); color:white; box-shadow: 0 8px 16px rgba(16, 185, 129, .4); }
    .play:focus-visible{ outline:none; box-shadow: var(--ring); }

    .content{ padding: 12px 14px 16px; display:flex; flex-direction:column; gap:6px; }
    .title{ font-weight:800; font-size: 16px; line-height:1.4; }
    .desc{ color: var(--ink-700); font-size: 14px; }
    .meta{ color: var(--muted); font-size: 12px; margin-top:4px; }

    .info{ padding: 18px; display:grid; gap: 16px; grid-template-columns: 1fr 1fr; }
    @media (max-width: 880px){ .info{ grid-template-columns: 1fr; } }

    .footer{ border-top: 1px dashed color-mix(in srgb, var(--brand-500) 25%, transparent); color: var(--muted); font-size:12px; padding: 18px 0 40px; }

    /* focus-visible polyfillish */
    :focus:not(:focus-visible) { outline: none; }

.subtitle {
  font-size: 1rem;        /* 少し小さめ */
  color: var(--ink-700);    /* グレー寄りで主張控えめ */
  margin: -6px 0 12px;      /* h1との間を詰める */
  font-weight: 500;         /* 中くらいの太さ */
}

.note {
  font-size: 0.8rem;
  color: var(--muted);
  margin-top: 6px;
}

/* PCでは横並び */
.menu {
  display: flex;
  gap: 12px;
}

/* ハンバーガーボタンは非表示 */
.menu-toggle {
  display: none;
  font-size: 28px;
  background: none;
  border: none;
  cursor: pointer;
}

.sp-br {
  display: none;
}

/* スマホ時のスタイル */
@media (max-width: 768px) {
  .menu {
    display: none;
    flex-direction: column;
    gap: 0;
    background: var(--card);
    position: absolute;
    top: 60px;   /* ヘッダー高さに応じて調整 */
    right: 0;
    padding: 12px;
    border-radius: 8px;
    box-shadow: var(--shadow);
  }
  .menu.show {
    display: flex;
  }
  .menu-toggle {
    display: block;
  }
  .sp-br {
    display: block;  /* ブロック要素として表示される＝改行になる */
  }
}

:root {
  --header-h: 72px;  /* ヘッダーの高さに合わせて調整 */
}

section[id] {
  scroll-margin-top: calc(var(--header-h) + 8px);
}

html {
  scroll-behavior: smooth; /* スムーズスクロール */
}

/* ====== ライトボックス再生用 ====== */
.lightbox {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.8);
  justify-content: center;
  align-items: center;
  z-index: 999;
}
.lightbox.active {
  display: flex;
}
.lightbox iframe {
  width: min(90vw, 960px);
  height: min(80vh, 540px);
  border: none;
  border-radius: 12px;
  box-shadow: 0 8px 32px rgba(0,0,0,.6);
}
.lightbox-close {
  position: absolute;
  top: 20px;
  right: 30px;
  color: #fff;
  font-size: 32px;
  font-weight: bold;
  cursor: pointer;
  background: none;
  border: none;
}

/* ====== 活用例リンク（学習指導案例） ====== */
#usage a {
  color: var(--brand-600);
  font-weight: 700;
  text-decoration: underline;
  text-decoration-color: var(--brand-300);
  text-underline-offset: 3px;
  transition: color 0.2s, text-decoration-color 0.2s;
}

#usage a:hover {
  color: var(--brand-700);
  text-decoration-color: var(--brand-500);
}