:root {
  --main-font: 'Ubuntu', sans-serif;
  --primary-bg: #f9f9f9;
  --card-bg: rgba(255, 255, 255, 0.1);
  --accent-color: #2196F3;
  --text-primary: #000;
  --text-secondary: #666;
  --shadow-light: 0 2px 8px rgba(0,0,0,0.1);
  --shadow-heavy: 0 10px 30px rgba(0, 0, 0, 0.15);
  --border-radius: 20px;
  --transition: all 0.3s ease;
}

@font-face {
  font-family: 'Ubuntu';
  src: url('Ubuntu.ttf') format('truetype');
  font-display: swap;
}

* {
  box-sizing: border-box;
}

body {
  font-family: var(--main-font);
  min-height: 100vh;
  margin: 0;
  background-color: var(--primary-bg);
  transition: background-color 1.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.menu {
  width: auto;
  height: 100px;
  background-color: var(--card-bg);
  padding: 15px;
  transition: transform 0.5s ease-in-out;
  position: fixed;
  border-radius: var(--border-radius);
  margin: 20px;
  box-shadow: var(--shadow-heavy);
  backdrop-filter: blur(10px);
  z-index: 3;
  display: flex;
  align-items: center;
  gap: 15px;
}

/* 浮动返回按钮 - 从左边弹出 */
.floating-back-button {
  position: fixed;
  left: 20px;
  top: 140px;
  background-color: rgba(255, 0, 0, 0.5);
  color: white;
  border: none;
  border-radius: var(--border-radius);
  padding: 10px 15px;
  font-size: 20px;
  cursor: pointer;
  transition: transform 0.3s ease, opacity 0.3s ease;
  box-shadow: 0 2px 8px rgba(255, 0, 0, 0.3);
  backdrop-filter: blur(5px);
  z-index: 2;
  opacity: 0;
  transform: translateX(-100px);
}

.floating-back-button:hover {
  background-color: rgba(255, 0, 0, 0.7);
  transform: translateX(5px) scale(1.05);
}

.floating-back-button.show {
  opacity: 1;
  transform: translateX(0);
}

.menu::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image: url('https://bing.img.run/rand_1366x768.php');
  background-size: cover;
  background-position: center;
  opacity: 0.7;
  z-index: -1; /* 层级-1：菜单背景，在菜单内容下面 */
  border-radius: var(--border-radius);
}

.menu-item {
  font-family: var(--main-font);
  background-color: rgba(255, 255, 255, 0.3);
  color: var(--text-primary);
  border-radius: var(--border-radius);
  padding: 15px;
  margin: 5px;
  font-size: 16px;
  cursor: pointer;
  border: none;
  transition: var(--transition);
  box-shadow: var(--shadow-light);
  backdrop-filter: blur(5px);
}

.menu-item:hover {
  background-color: #bbb;
  transform: translateY(-3px) scale(1.02);
  box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

.menu-item.selected {
  transform: translateY(5px) scale(1.05);
  background-color: var(--card-bg);
  font-weight: bold;
  padding-bottom: 40px;
  box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

/* 返回按钮样式 */
.menu-item.back-button {
  background-color: rgba(255, 0, 0, 0.5); /* 半透明红色 */
  color: white;
  border-radius: var(--border-radius);
  padding: 10px 15px; /* 上下缩小5px，左右保持不变 */
  margin: 5px;
  font-size: 20px; /* 增大字体使符号更清晰 */
  cursor: pointer;
  border: none;
  transition: var(--transition);
  box-shadow: 0 2px 8px rgba(255, 0, 0, 0.2); /* 红色阴影 */
  backdrop-filter: blur(5px);
  display: none; /* 默认隐藏 */
  font-weight: bold;
  min-width: 50px; /* 固定宽度确保圆形 */
  text-align: center;
}

.menu-item.back-button:hover {
  background-color: rgba(255, 0, 0, 0.7); /* 悬停时红色更明显 */
  transform: translateY(-3px) scale(1.02);
  box-shadow: 0 5px 15px rgba(255, 0, 0, 0.3);
}

.content {
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: #ffffff;
  transition: background-color 0.8s ease;
  width: 100%;
  height: 100vh;
  padding: 20px;
  box-sizing: border-box;
  overflow-y: auto; /* 允许内容滚动 */
  z-index: 1; /* 层级1：主要内容区域 */
}

/* 讨论区容器样式 */
.discussion-container {
  width: 100%;
  height: auto;
  padding: 40px 20px;
  text-align: center;
  display: flex;
  flex-direction: column;
  justify-content: flex-start; /* 改为从顶部开始 */
  align-items: center;
  min-height: auto;
}

.discussion-container h2 {
  font-size: 2.5rem;
  margin-bottom: 40px;
  color: var(--text-primary);
  font-weight: 300;
}

/* 讨论区网格布局 */
.discussion-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 30px;
  max-width: 800px;
  margin: 0 auto;
}

/* 讨论卡片样式 */
.discussion-card {
  background-color: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 30px;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: var(--shadow-light);
  backdrop-filter: blur(5px);
  border: 1px solid rgba(255, 255, 255, 0.2);
  z-index: 2; /* 层级2：卡片内容，在内容区域之上 */
}

.discussion-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-heavy);
  background-color: rgba(255, 255, 255, 0.2);
}

.discussion-card h3 {
  font-size: 1.5rem;
  margin-bottom: 15px;
  color: var(--text-primary);
  font-weight: 400;
}

.discussion-card p {
  color: var(--text-secondary);
  line-height: 1.6;
  font-size: 0.95rem;
}

/* 文章列表样式 */
.article-list-container {
  width: 100%;
  max-width: 1000px;
  padding: 40px 20px;
  margin: 0 auto;
}

.article-header {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin-bottom: 30px;
  border-bottom: 2px solid #f0f0f0;
  padding-bottom: 20px;
  text-align: center;
}

.article-header .back-button {
  background-color: var(--card-bg);
  border: none;
  border-radius: var(--border-radius);
  padding: 10px 20px;
  cursor: pointer;
  transition: var(--transition);
  margin-bottom: 15px;
  margin-right: 20px;
  font-size: 1rem;
  box-shadow: var(--shadow-light);
}

.back-button:hover {
  background-color: rgba(255, 255, 255, 0.3);
  transform: translateX(-3px);
}

.article-header h2 {
  font-size: 2rem;
  color: var(--text-primary);
  margin: 0;
}

.articles-grid {
  display: flex;
  flex-direction: column;
  gap: 15px;
}

.article-item {
  background-color: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 20px;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: var(--shadow-light);
  backdrop-filter: blur(5px);
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.article-item:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-heavy);
  background-color: rgba(255, 255, 255, 0.2);
}

.article-item h3 {
  font-size: 1.3rem;
  margin: 0 0 10px 0;
  color: var(--text-primary);
}

.article-date {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.no-articles {
  text-align: center;
  color: var(--text-secondary);
  font-style: italic;
  padding: 40px;
}

/* 文章详情样式 */
.article-detail-container {
  width: 100%;
  max-width: 900px;
  padding: 40px 20px;
  margin: 0 auto;
}

.article-content {
  background-color: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 30px;
  box-shadow: var(--shadow-light);
  backdrop-filter: blur(5px);
  line-height: 1.8;
}

.article-content h1 {
  font-size: 2.2rem;
  margin-bottom: 20px;
  color: var(--text-primary);
  border-bottom: 2px solid #f0f0f0;
  padding-bottom: 15px;
}

.article-content p {
  margin-bottom: 15px;
  color: var(--text-primary);
}

.article-content b {
  color: #333;
  font-weight: 600;
}

/* 响应式设计 */
@media (max-width: 768px) {
  .discussion-grid {
    grid-template-columns: 1fr;
    max-width: 500px;
  }
  
  .discussion-container h2 {
    font-size: 2rem;
  }
  
  .discussion-card h3 {
    font-size: 1.3rem;
  }
  
  .article-list-container,
  .article-detail-container {
    padding: 20px 15px;
  }
  
  .article-header {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .back-button {
    margin-right: 0;
    margin-bottom: 15px;
  }
  
  .article-content h1 {
    font-size: 1.8rem;
  }
}


.content-item {
  display: none;
  width: 100%;
  height: 100%;
  padding-top: 20px;
}

.content-item.active {
  display: flex;
  flex-direction: column;
}

iframe {
  width: 100%;
  height: 100%;
  border: none;
}

.audio-control-container {
  display: flex;
  align-items: center;
  margin-top: 10px;
  position: relative;
}

.audio-control {
  width: 60px;
  height: 60px;
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  cursor: pointer;
  position: relative;
}

.audio-control::before {
  content: "▶";
  color: var(--text-primary);
  font-size: 30px;
  
}

.audio-control.playing::before { content: "❚❚"; }
.audio-control.paused::before { content: "▶"; }

.playback-status {
  color: black;
  font-size: 18px;
  text-align: left;
  position: absolute;
  left: 50%;
  white-space: nowrap;
  opacity: 0;
  width: auto;
  background-color: rgba(255, 255, 255);
  padding: 10px;
  border-radius: var(--border-radius);
  transition: transform 1s ease, opacity 1s ease;
}

.playback-status.show {
  opacity: 1;
  transform: translateX(100px);

}

.lyric-text {
  text-align: left;
  font-size: 16px;
  color: #000;
  white-space: nowrap;
  max-height: 25px;
  overflow: hidden;
}

.image-container {
  float: left;
  margin: 10px;
  padding: 10px;
  border: none;
  max-width: 40%;
}

.title-image {
  width: 50px;
  height: auto;
  display: block;
}

.mobile-menu-btn {
  display: none;
  position: fixed;
  top: 15px;
  left: 15px;
  width: 40px;
  height: 40px;
  background: rgba(255,255,255,0.3);
  border-radius: 40%;
  text-align: center;
  line-height: 43px;
  font-size: 20px;
  z-index: 9999;
  box-shadow: var(--shadow-light);
  cursor: pointer;
}

@media (max-width: 768px) {
  .mobile-menu-btn { display: block; }
  .menu { width: auto; }
  .menu.active { transform: translateX(-100%); }
  .title-image { width: 40px;  }
  .audio-control { display: none; }
  .content { height: 100%; }
}