body {
  margin: 0;
  font-family: "Yu Mincho", "Hiragino Mincho ProN", serif;
  background-image: url("wallppr027.gif");
}

/* ヘッダー */
.header {
  text-align: center;
  padding: 20px;
  border-bottom: 1px solid #ccc;

}

/* レイアウト */
.container {
  display: flex;
  width: 100%;
  max-width: 1200px;
  margin: auto;
}

.wrapper {
  max-width: 1100px;
  margin: 30px auto;
  padding: 20px;
  background-color: white;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  border-radius: 8px;
}


/* サイドバー */
.sidebar {
  padding-right: 15px;
  background-color: #eef5ff;
  flex-shrink: 0;   /* ←これが超重要 */
}

.menu {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.menu a {
  display: block;
  text-align: center;
  padding: 6px;
  border-radius: 8px;
  transition: 0.2s;
}

.menu a:hover {
  background: #dde9ff;
}

.materials a{
  font-size: 20px;
}

.home-link {
  margin-bottom: 15px;
}

.home-link a {
  display: block;
  background: #698fe0;
  color: white;
  font-weight: bold;
  padding: 10px;
  border-radius: 6px;
  text-align: center;
  box-shadow: 0 2px 5px rgba(0,0,0.2)
}

.home-link a:hover {
  background: #1f3668;
}

summary {
  font-size: 18px;
  font-weight: bold;
  padding: 8px;
  background: #eef5ff;
  border-radius: 6px;
}



/* 画像ボタン */
.menu img {
  width: 220px;
  height: auto;
  border: none;
  transition: 0.2s;
  border-bottom: 1px solid #ccc;
}

@media (max-width: 768px){
  .menu img {
    width: 100%;
    max-width: 350px;
    border-bottom: 1px solid #ccc;
  }

  .menu a{
    display: block;
    padding: 12px;
    margin: 12px 0;
    }
}

/* ホバー効果（軽く光る） */
.menu img:hover {
  opacity: 0.8;
}

/* メイン */
.main {
  flex: 1;
  min-width: 0;   /* ←これ重要 */
}


.theme {
  padding-left: 40px;
  color: #333;
  font-size: 24px;
}

.subtitle {
  padding-left: 40px;
  margin: 20px 0;
}

.subtitle ul {
  padding-left: 20px;
}

.row {
  display: flex;
  align-items: center;
  margin-bottom: 15px;
}

.month {
  width: 80px;
  font-weight: bold;
  text-align: center;
}

.grade {
  margin-top: 20px;
}

.links a {
  margin-right: 15px;
}

.link-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 15px;
  margin-bottom: 20px;
}

.link-grid a {
  display: block;
  text-align: center;
  padding: 10px;
  background: #f9f9f9;
  border-radius: 6px;
  text-decoration: none;
}

.link-grid a:hover {
  background: #eef5ff;
}

/* スライド */
.swiper {
  width: 90%;
  max-width: 800px;
  aspect-ratio: 16 / 9;
}

.swiper img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 8px;
  display: block;
}

/* 更新 */
.updates {
  margin-top: 30px;
  padding-left: 20px;
}

.updates ul {
  padding-left: 20px;
}


/* 資料ページ用ボックス */
.content-box {
  background: #f9f9f9;
  padding: 10px;
  margin: 15px 0;
  margin-left: 30px;
  border-left: 5px solid #2c4a8a;
}

/* リンクをボタン風に */
.content-box a {
  text-decoration: none;
  font-size: 18px;
  color: #2c4a8a;
  font-weight: bold;
}

.content-box a:hover {
  text-decoration: underline;
}


/* フッター */
.footer {
  text-align: center;
  padding: 10px;
}

/* スマホ対応 */
@media (max-width: 768px) {
  .wrapper {
    padding: 10px;
  }
  
  .container {
    flex-direction: column;
  }

  .sidebar {
    width: 100%;
  }

  .swiper {
    width: calc(100% - 20px);
    margin: 20px auto;
  aspect-ratio: 4 / 3;
  }

  .swiper img {
    object-fit: contain;
    background: #000;
  }
}