@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@300;400;500;700&display=swap');

/* === 基本スタイル === */
body {
  margin: 0;
  background-color: #fff;
  color: #0c7bbb;
  font-family: 'Roboto', 'Segoe UI', 'Helvetica Neue', sans-serif;
}

html {
  scroll-behavior: smooth;
}

/* === レイアウト === */
.container {
  display: flex;
  flex-wrap: wrap;
  min-height: 100vh;
}

.sidebar {
  width: 180px;
  background-color: #0c7bbb;
  padding: 1em 15px 0;
  position: fixed;
  top: 0;
  bottom: 0;
  overflow-y: auto;
  box-shadow: 2px 0 5px rgba(0, 0, 0, 0.1);
  color: #fff;
}

.sidebar h2 {
  margin: 0.5em 0 1em;
  color: #fff;
  border-bottom: 1px solid rgba(255, 255, 255, 0.3);
  padding-bottom: 0.5em;
  font-size: 1.3em;
}

.sidebar ul {
  list-style: none;
  padding: 0;
  margin-top: 1.5em;
}

.sidebar li {
  margin: 1em 0;
  font-weight: 500;
  cursor: pointer;
  transition: transform 0.2s ease;
}

.sidebar li:hover {
  transform: translateX(5px);
}

.sidebar li a {
  color: #fff;
  text-decoration: none;
  display: block;
  padding: 0.3em 0;
  transition: color 0.3s ease;
}

.sidebar li a:hover {
  color: #7a99cf;
}

.content {
  flex: 1;
  min-width: 0;
  margin-left: 200px;
  padding: 1.5em 25px;
  overflow-y: auto;
  background-color: #f9fcff;
  color: #333;
  font-size: 1.05em;
  line-height: 1.7;
}

/* === セクション === */
.section {
  border-left: 5px solid #0c7bbb;
  padding: 1em 1.2em;
  margin: 2em 0;
  background-color: rgba(122, 153, 207, 0.1);
  border-radius: 6px;
}

.content h1 {
  margin-bottom: 0.5em;
  color: #0c7bbb;
  border-bottom: 2px solid #7a99cf;
  padding-bottom: 0.3em;
}

.content h2,
.content h3 {
  margin-top: 1.2em;
  margin-bottom: 0.5em;
  color: #0c7bbb;
}

.content p,
.content ul,
.content ol {
  font-size: 1em;
  line-height: 1.7;
  margin: 0.8em 0;
  color: #333;
}

.content li {
  line-height: 1.7;
  margin-bottom: 0.5em;
}

/* === 補助要素 === */
.highlight {
  text-decoration: underline;
  text-decoration-color: #7a99cf;
  font-weight: bold;
  color: #0c7bbb;
}

.contact {
  margin-top: 0.5em;
  font-size: 0.95em;
  color: #555;
}

#language-switcher {
  margin-top: 1.5em;
  text-align: center;
}

#lang-btn {
  background-color: #7a99cf;
  color: white;
  border: none;
  padding: 0.6em 1.5em;
  border-radius: 20px;
  font-weight: bold;
  cursor: pointer;
  transition: background-color 0.3s ease, transform 0.2s ease;
}

#lang-btn:hover {
  background-color: #0c7bbb;
  transform: translateY(-2px);
}

footer {
  text-align: center;
  font-size: 0.85em;
  color: #999;
  padding: 1em;
  margin-top: 4em;
  border-top: 1px solid #eee;
}

.sidebar footer {
  text-align: center;
  padding: 1em 0;
  margin-top: 2em;
  border-top: 1px solid rgba(255, 255, 255, 0.2);
}

.sidebar footer a {
  color: #fff;
  text-decoration: none;
  font-size: 0.9em;
  transition: color 0.3s ease;
}

.sidebar footer a:hover {
  color: #7a99cf;
}

.no-underline {
  text-decoration: none;
}

/* === カスタムボタン === */
.custom-button {
  display: inline-block;
  font-size: 80%;
  font-weight: bold;
  padding: 0.3em 1em;
  margin-left: 0.8em;
  vertical-align: middle;
  background-color: #fff;
  color: #0c7bbb;
  border: 1px solid #0c7bbb;
  border-radius: 0.5em;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 0.3s, color 0.3s, border-color 0.3s, box-shadow 0.2s, transform 0.2s;
}

.custom-button:hover {
  background-color: #0c7bbb;
  color: #fff;
  border-color: #0c7bbb;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
  transform: translateY(-2px);
}

.custom-button:active {
  background-color: #095f8a;
  border-color: #095f8a;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
  transform: translateY(0);
}

/* === レスポンシブ対応 === */
@media (max-width: 768px) {
  .sidebar {
    position: relative;
    width: 100%;
    box-shadow: none;
    padding: 1em 15px;
  }

  .sidebar ul {
    display: flex;
    justify-content: space-around;
    margin-top: 1em;
    flex-wrap: wrap;
  }

  .sidebar li {
    margin: 0.5em 0.8em;
    text-align: center;
  }

  .sidebar li:hover {
    transform: none;
  }

  .content {
    margin-left: 0;
    padding: 1.5em;
  }

  #language-switcher {
    margin: 0.5em 0 1.5em;
  }
}

/* === MathJax 調整 === */
mjx-container[jax="CHTML"][display="true"] {
  display: block;
  text-align: left !important;
  margin-left: 3em;
}