html, body, * {
  font-size: 110%;
}

/* =========================
   PC レイアウト
========================= */
@media screen and (min-width: 720px) {

  body {
    background:
      repeating-linear-gradient(0deg, #000 0, #000 2px, #111 2px, #111 4px),
      repeating-linear-gradient(90deg, #000 0, #000 2px, #111 2px, #111 4px);
    background-size: 4px 4px;
    background-attachment: fixed;

    padding: 100px 10px 100px 10px;
    letter-spacing: 0.05em;
  }

}

/* =========================
   SP レイアウト
========================= */
@media screen and (max-width: 720px) {

  body {
    background:
      repeating-linear-gradient(0deg, #000 0, #000 2px, #111 2px, #111 4px),
      repeating-linear-gradient(90deg, #000 0, #000 2px, #111 2px, #111 4px);
    background-size: 4px 4px;
    background-attachment: scroll;

    padding: 110px 0px 100px 0px;
  }

}

/* =========================
   共通デザイン
========================= */

/* PC/SP 切り替え */
.show-pc { display: block !important; }
.show-sp { display: none !important; }

@media only screen and (max-width: 720px) {
  .show-pc { display: none !important; }
  .show-sp { display: block !important; }
}

/* ヘッダー帯 */
.site-header {
  z-index: 9998;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;

  height: 90px;

  display: flex;
  justify-content: space-between;
  align-items: center;

  background-color: rgba(32, 32, 32, 0.9);
  padding: 0;
}

/* 現在ページバッジ */
.current-page-badge {
  position: sticky;
  top: 90px;

  display: inline-flex;
  align-items: center;

  height: 40px;
  padding: 0 20px;

  background-color: #0000ff;
  border: 2px solid #ffffff;
  border-radius: 6px;
  color: #ffffff;
  font-weight: bold;
  
  text-decoration: none;
}

/* セクション背景 */
.section-box {
  background-color: rgba(154, 154, 154, 0.7);
  padding: 10px;
  margin: 15px 0;
}

/* ナビボタン */
.btn-nav {
  display: inline-block;
  padding: 5px 10px;
  color: #fff;
  text-align: center;
  background-color: #962e0e;
  border-radius: 8px;
  cursor: pointer;
  border: 3px solid #ffffff;
  image-rendering: pixelated;
  box-shadow: 0 3px #5a1a0a;
  font-size: 95%;
}

.nav-buttons {
  display: flex;
  justify-content: center;
  gap: 10px;
}

.nav-box {
  display: flex;
  justify-content: center;
  gap: 12px;
}

/* MENU ボタン */
.btn-menu {
  color: #ffffff;
  font-weight: bold;
  background: #962e0e;
  width: 120px;
  font-size: 120%;
  padding: 10px 0;
  border-radius: 5px;
  cursor: pointer;
  margin: 10px 50px 10px 0px;
  border: 3px solid #ffffff;
  box-shadow: 0 3px #5a1a0a;
}

/* ダウンロードボタン */
.btn-download {
  width: 100%;
  padding: 4px 0;
  font-size: 12px;
  font-weight: bold;
  font-family: "MS PGothic", monospace;
  background: #d00000;
  color: #fff;
  border: 2px solid #000;
  border-radius: 0;
  box-shadow: 0 2px 0 #000;
  cursor: pointer;
}

.btn-download:active {
  box-shadow: none;
  transform: translateY(2px);
}

/* =========================
   アイテムグリッド（修正版）
========================= */
.item-grid {
  display: grid;
  gap: 24px; 
  grid-template-columns: repeat(auto-fit, minmax(360px, 1fr));
  justify-content: stretch; /* ← 中央寄せを解除 */
  max-width: 1800px;
  margin: 0 auto;
}

/* カードを完全に隣接させる */
.item-card {
  width: 100%;   
  margin: 20px;
  padding: 2px;
  background: #fff;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
}


@media screen and (min-width: 720px) {
    .item-card { width: 400px; }
}

/* YouTube プレイヤー */
.yt-player {
  width: 100%;
  aspect-ratio: 16 / 9; /* ← これで高さが確定して CLS が消える */
  height: auto;
  overflow: hidden;
}


.btn-download {
  margin-top: 6px;
  width: 100%;
  padding: 8px 0;
  font-size: 14px;
}

/* footer */
footer {
  margin: 15px 0px;
}

.footer-license {
  text-align: center;
  background-color: rgba(32, 32, 32, 0.9);
  color: #ffffff;
}

.page-title-center {
  text-align: center;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}