/* 全体 */
body {
  font-family: "Helvetica Neue", sans-serif;
  font-size: 20px;
  margin: 0;
  background: #f8f9fb;
  color: #333;
  line-height: 1.8;
}

/* メニューボタン（右上） */
#menuBtn {
  position: fixed;
  top: 20px;
  right: 20px;
  font-size: 26px;
  background: #2c3e50;
  color: white;
  padding: 10px 14px;
  border-radius: 8px;
  cursor: pointer;
  z-index: 1001;
  box-shadow: 0 4px 10px rgba(0,0,0,0.2);
  transition: 0.3s;
}

#menuBtn:hover {
  background: #34495e;
  transform: scale(1.05);
}

/* サイドメニュー */
#sideMenu {
  position: fixed;
  top: 0;
  right: -250px;
  width: 250px;
  height: 100%;
  background: #2c3e50;
  color: white;
  padding-top: 60px;
  transition: 0.3s;
  z-index: 999;
}

#sideMenu.open {
  right: 0;
}

#sideMenu ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

#sideMenu li {
  padding: 15px 20px;
}

#sideMenu a {
  color: white;
  text-decoration: none;
  font-size: 18px;
}

#sideMenu a:hover {
  color: #ddd;
}

/* 背景オーバーレイ */
#overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.4);
  display: none;
  z-index: 998;
}

#overlay.show {
  display: block;
}

/* ヘッダー */
header {
  background: white;
  color: #222;

  text-align: center;

  padding: 35px 20px 20px;

  border-bottom: 1px solid #dcdcdc;
}

header h1 {
  font-family: "Kaisei Tokumin", serif;
  font-size: 64px;
  font-weight: normal;

  margin: 0;

  letter-spacing: 0.08em;
}

header p {
  font-family: "Kaisei Tokumin", serif;
  font-size: 20px;

  color: #666;

  margin-top: 5px;
  margin-bottom: 0;
}

/* ナビゲーションバー */
.navbar {
  display: flex;
  justify-content: center;

  background: white;

  border-top: 1px solid #dcdcdc;
  border-bottom: 1px solid #dcdcdc;

  margin: 0;
  padding: 0;
}

.navbar a {
  display: flex;
  align-items: center;
  justify-content: center;

  min-width: 180px;

  padding: 14px 25px;

  text-decoration: none;

  color: #2e4357;

  font-size: 18px;
  font-weight: 500;

  border-right: 1px solid #e5e5e5;

  position: relative;

  transition: all 0.2s ease;
}

.navbar a:first-child {
  border-left: 1px solid #e5e5e5;
}

.navbar a:hover {
  background: #f3f7fa;
}

.navbar a.active {
  background: #f3f7fa;
  color: #243746;
  font-weight: bold;
}

.navbar a::after {
  content: "";

  position: absolute;
  left: 50%;
  bottom: 0;

  width: 0;
  height: 2px;

  background: #5f7d95;

  transform: translateX(-50%);

  transition: width 0.25s ease;
}

.navbar a:hover::after,
.navbar a.active::after {
  width: 60%;
}

/* セクション */
section {
  max-width: 900px;
  margin: 40px auto;
  background: white;
  padding: 35px;
  border-radius: 12px;
  box-shadow: 0 5px 20px rgba(0,0,0,0.05);
}

section p {
  font-size: 20px;
}

/* 画像 */
img {
  max-width: 100%;
  height: auto;
  border-radius: 10px;
}

/* 見出し */
h2 {
  border-left: 6px solid #2c3e50;
  padding-left: 15px;
  font-size: 34px;
  margin-bottom: 25px;
  color: #2c3e50;
}

/* テーブル */
table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 20px;
}

th,
td {
  border: 1px solid #ccc;
  padding: 15px;
  text-align: center;
  font-size: 20px;
}

th {
  background: #2c3e50;
  color: white;
}

/* ボタン */
.button {
  display: inline-block;
  background: #2c3e50;
  color: white;
  padding: 12px 24px;
  border-radius: 8px;
  text-decoration: none;
  transition: 0.3s;
}

.button:hover {
  background: #34495e;
}

/* フッター */
footer {
  text-align: center;
  padding: 30px;
  font-size: 16px;
  color: #777;
}

/* スマホ対応 */
@media (max-width: 768px) {

  body {
    font-size: 16px;
  }

  /* ヘッダー */
  header {
    background: white;
    color: #222;

    text-align: center;

    padding: 25px 20px 10px;

    border-bottom: 1px solid #dcdcdc;
  }

  /* 塾名 */
  header h1 {
    font-family: "Kaisei Tokumin", serif;

    font-size: 48px;
    font-weight: normal;

    margin: 0;
    letter-spacing: 0.08em;
  }

  /* since1987 */
  header p {
    font-family: "Kaisei Tokumin", serif;

    font-size: 18px;
    color: #666;

    margin-top: 5px;
    margin-bottom: 0;
  }

  h2 {
    font-size: 24px;
  }

  section {
    margin: 12px;
    padding: 20px;
  }

  section p {
    font-size: 16px;
  }

  th,
  td {
    font-size: 14px;
    padding: 8px;
  }

  /* スマホ用ナビ */
  .navbar {
    display: flex;
    flex-direction: column;

    background: #e8eff5;

    border-bottom: 1px solid #bfcddb;

    margin: 0;
    gap: 0;
  }

  .navbar a {
    display: flex;
    align-items: center;
    justify-content: center;

    width: 100%;

    padding: 10px 5px;

    color: #2e4357;

    font-size: 16px;
    font-weight: 500;

    border-bottom: 1px solid #c7d3df;
  }

  .navbar a:hover,
  .navbar a:active {
    background: #d7e4ef;
  }

  .navbar a.active {
    background: #6b879d;
    color: white;
    font-weight: bold;
  }

  .navbar a.active::after {
    content: "";

    position: absolute;

    width: 32px;
    height: 2px;

    margin-top: 24px;

    background: rgba(255,255,255,0.8);

    border-radius: 2px;
  }

  .navbar a:last-child {
    border-bottom: none;
  }
}