/* === 全体設定 === */
body {
  font-family: "Helvetica Neue", "Hiragino Kaku Gothic ProN", sans-serif;
  margin: 0;
  padding: 0;
  color: #333;
  background-color: #fdfdfd;
  line-height: 1.6;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* === ヘッダー === */
header {
  background-color: #ffffff;
  border-bottom: 1px solid #ddd;
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
header .logo img {
  max-height: 50px;
}
header nav ul {
  list-style: none;
  display: flex;
  margin: 0;
  padding: 0;
}
header nav li {
  margin-left: 1rem;
}
header nav a {
  color: #0078d7;
  text-decoration: none;
}
header nav a:hover {
  text-decoration: underline;
}

/* === mainコンテンツ === */
main {
  max-width: 960px;
  margin: 40px auto;
  padding: 0 20px;
  background-color: #fff;
}

/* === セクションタイトル === */
main h1, main h2, main h3 {
  color: #222;
  margin-top: 2rem;
}
main h1 {
  font-size: 2rem;
  border-bottom: 2px solid #ccc;
  padding-bottom: 0.5rem;
}
main h2 {
  font-size: 1.6rem;
  margin-top: 1.5rem;
}
main h3 {
  font-size: 1.3rem;
  margin-top: 1rem;
}

/* === 商品リスト === */
.item-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}
.item {
  border: 1px solid #ddd;
  border-radius: 4px;
  padding: 1rem;
  background: #f9f9f9;
  transition: box-shadow 0.3s ease;
}
.item:hover {
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}
.item h3 {
  font-size: 1.1rem;
  margin-bottom: 0.5rem;
}
.item p {
  font-size: 0.9rem;
  color: #555;
}

/* === リスト要素用 === */
ul.usage-list {
  padding-left: 1.5rem;
}
ul.usage-list li {
  list-style: disc;
  margin-bottom: 0.5rem;
}

/* === フッター === */
footer {
  background-color: #ffffff;
  border-top: 1px solid #ddd;
  padding: 1rem;
  text-align: center;
  font-size: 0.875rem;
  color: #666;
}

/* === レスポンシブ対応 === */
@media (max-width: 600px) {
  main {
    padding: 0 10px;
  }
  .item-list {
    grid-template-columns: 1fr;
  }
}