:root {
  --bg-color: #000000;
  --bg-color-dark: #000000;
  --text-light: #ffffff;
  --text-dark: #ffffff;
  --text-muted: #b0bec5;
  --card-bg: #000000;
  --accent-cyan: #00e5ff;
  --accent-gold: #ffc107;
  --accent-orange: #ff9800;
  --border-gold: #ffeb3b;
  --border-cyan: #00838f;
  --border-color: rgba(255, 235, 59, 0.4);
  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.5);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.7);
  --shadow-lg: 0 0 15px rgba(255, 235, 59, 0.15);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Hiragino Kaku Gothic ProN", "Meiryo", monospace;
  background-color: var(--bg-color);
  color: var(--text-light);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent-cyan);
  transition: opacity 0.2s ease;
}

a:hover {
  opacity: 0.8;
  color: #80d8ff;
}

/* レイアウト */
.container {
  max-width: 680px;
  margin: 0 auto;
  padding: 24px 16px;
  text-align: center;
}

.container-wide {
  max-width: 800px;
  margin: 0 auto;
  padding: 24px 16px;
}

/* ナビゲーション */
.lang-nav {
  text-align: right;
  margin-bottom: 16px;
  font-size: 0.95rem;
}

.lang-nav a {
  background: #001f24;
  border: 1px solid var(--border-cyan);
  color: var(--accent-cyan);
  padding: 6px 14px;
  border-radius: 20px;
  text-decoration: none;
  font-weight: 500;
  display: inline-block;
}

.lang-nav a:hover {
  background: #004d40;
  opacity: 1;
}

.doc-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 20px;
}

.doc-nav a {
  color: var(--accent-cyan);
  text-decoration: none;
  font-weight: 500;
  background: #001f24;
  border: 1px solid var(--border-cyan);
  padding: 6px 14px;
  border-radius: 20px;
  display: inline-flex;
  align-items: center;
}

.doc-nav a:hover {
  background: #004d40;
  opacity: 1;
}

.app-webview .doc-nav {
  justify-content: flex-end;
  margin-bottom: 12px;
}

.app-webview .doc-nav a[href="../index.html"],
.app-webview .doc-nav a[href="../index_en.html"] {
  display: none;
}

.app-webview .doc-card {
  border: 0;
  border-radius: 0;
  box-shadow: none;
}

/* ヘッダー・ロゴ */
header {
  margin-bottom: 24px;
}

.app-icon {
  width: 72px;
  height: 72px;
  border-radius: 16px;
  box-shadow: var(--shadow-md);
  vertical-align: middle;
}

h1 {
  font-size: 2.2rem;
  margin: 12px 0 16px;
  font-weight: bold;
  letter-spacing: 0.5px;
  color: var(--accent-cyan);
}

/* YouTube レスポンシブ動画ラッパー */
.video-wrapper {
  position: relative;
  width: 100%;
  padding-top: 56.25%; /* 16:9 Aspect Ratio */
  margin: 24px 0;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  background: #000;
}

.video-wrapper iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

/* ボタンスタイル */
.download-section {
  margin: 28px 0;
}

.btn-link {
  display: inline-block;
  width: 90%;
  max-width: 380px;
  margin: 8px 0;
  padding: 14px 20px;
  background-color: var(--card-bg);
  color: var(--accent-gold);
  border: 2px solid var(--border-gold);
  font-weight: bold;
  font-size: 1.05rem;
  text-decoration: none;
  border-radius: 30px;
  box-shadow: var(--shadow-md);
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.btn-link:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  opacity: 1;
}

.help-text {
  font-size: 0.85rem;
  margin-top: 6px;
  opacity: 0.95;
}

/* ニュース・メディア掲載セクション */
.news-section {
  margin: 28px 0;
  padding: 16px;
  background: #001f24;
  border: 1px solid var(--border-cyan);
  border-radius: 4px;
  backdrop-filter: blur(4px);
}

.news-section p {
  margin: 8px 0;
  font-size: 1rem;
}

.news-section a {
  text-decoration: underline;
  font-weight: 500;
}

/* サブリンク（規約・問い合わせなど） */
.sub-links {
  margin-top: 32px;
  padding-top: 20px;
  border-top: 1px solid var(--border-color);
}

.sub-links p {
  margin: 10px 0;
  font-size: 0.95rem;
}

.sub-links a {
  margin: 0 4px;
  text-decoration: underline;
}

/* ドキュメント・利用規約・ポリシー用カード */
.doc-card {
  background-color: var(--card-bg);
  color: var(--text-dark);
  border: 3px double var(--border-gold);
  border-radius: 4px;
  padding: 28px 24px;
  box-shadow: var(--shadow-lg);
  text-align: left;
  line-height: 1.75;
}

.doc-card h1 {
  color: var(--accent-cyan);
  font-size: 1.6rem;
  margin: 0 0 16px 0;
  text-align: center;
  border-bottom: 1px solid var(--border-cyan);
  padding-bottom: 12px;
}

.doc-card .doc-date {
  text-align: right;
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 24px;
}

.doc-card h2 {
  font-size: 1.2rem;
  color: var(--accent-gold);
  margin: 28px 0 12px;
  padding-left: 8px;
  border-left: 4px solid var(--accent-orange);
}

.doc-card h3 {
  font-size: 1.05rem;
  color: var(--accent-gold);
  margin: 20px 0 8px;
}

.doc-card p {
  margin: 12px 0;
  font-size: 0.95rem;
  color: #f1f5f9;
}

.doc-card a {
  color: var(--accent-cyan);
  text-decoration: underline;
}

.doc-card a:hover {
  color: #80d8ff;
}

.doc-card ol,
.doc-card ul {
  padding-left: 24px;
  margin: 12px 0;
}

.doc-card li {
  margin-bottom: 8px;
  font-size: 0.95rem;
  color: #f1f5f9;
}

.doc-card pre {
  background: #001f24;
  border: 1px solid #004d40;
  border-radius: 4px;
  padding: 16px;
  overflow-x: auto;
  font-size: 0.85rem;
  line-height: 1.5;
  color: #e0f7fa;
  font-family: SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  white-space: pre-wrap;
  word-break: break-word;
}

/* フッター */
footer {
  margin-top: 40px;
  padding: 20px 0;
  font-size: 0.85rem;
  text-align: center;
  opacity: 0.9;
}

/* 404 特化スタイル */
.error-card {
  background-color: var(--card-bg);
  color: var(--text-dark);
  border: 3px double var(--border-gold);
  border-radius: 4px;
  padding: 40px 24px;
  box-shadow: var(--shadow-lg);
  text-align: center;
  margin: 40px auto;
  max-width: 500px;
}

.error-code {
  font-size: 4rem;
  font-weight: 800;
  color: var(--accent-cyan);
  margin: 0;
  line-height: 1;
}

.error-title {
  font-size: 1.5rem;
  margin: 12px 0 16px;
  color: var(--accent-gold);
}

.error-desc {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 28px;
  line-height: 1.6;
}

@media (max-width: 600px) {
  h1 {
    font-size: 1.8rem;
  }
  .doc-card {
    padding: 24px 16px;
  }
  .doc-card h1 {
    font-size: 1.4rem;
  }
}