/* Reset & 基本布局 */
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: #f0f2f5;
  color: #333;
  line-height: 1.5;
  padding: 2rem;
}
.tab-container {
  max-width: 720px;
  margin: 0 auto;
  background: #fff;
  border-radius: 8px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.1);
  overflow: hidden;
}

/* Tabs 导航 */
.tabs {
  display: flex;
  background: #fafbfc;
  border-bottom: 1px solid #e1e4e8;
}
.tab-btn {
  flex: 1;
  padding: 1rem;
  text-align: center;
  cursor: pointer;
  background: none;
  border: none;
  font-size: 1rem;
  transition: background 0.2s;
}
.tab-btn:hover {
  background: #f6f8fa;
}
.tab-btn.active {
  background: #fff;
  border-bottom: 3px solid #0070f3;
  color: #0070f3;
  font-weight: 600;
}

/* 内容区 */
.tab-content {
  padding: 1.5rem;
}
.tab-panel { display: none; }
.tab-panel.active { display: block; }

/* 下载链接样式 */
.download-link {
  display: inline-block;
  margin: 1rem 0 1.5rem;
  padding: 0.75rem 1.5rem;
  background: #0070f3;
  color: #fff;
  text-decoration: none;
  border-radius: 4px;
  font-weight: 500;
  transition: background 0.2s;
}
.download-link:hover {
  background: #005ec2;
}

/* 教程视频 */
.tutorial-video {
  width: 100%;
  max-height: 400px;
  border-radius: 6px;
  background: #000;
}