body {
  font-family: "Segoe UI", "Microsoft YaHei", sans-serif;
  line-height: 1.6;
  color: #333;
  max-width: 1100px;
  margin: 0 auto;
  padding-left: 260px; /* 给左侧导航预留空间 */
  background-color: #fafafa;
}
h1, h2, h3, h4 {
  color: #2c3e50;
}
h1 {
  text-align: center;
  margin: 20px 0 30px;
  border-bottom: 2px solid #3498db;
  padding-bottom: 10px;
}
h2 {
  margin-top: 30px;
  border-left: 4px solid #3498db;
  padding-left: 10px;
}
h3 {
  margin-top: 20px;
  color: #2980b9;
}
h4 {
  margin-top: 16px;
}
ul, ol {
  padding-left: 22px;
}
li {
  margin-bottom: 6px;
}
pre, code, textarea {
  background-color: #f4f4f4;
  border-radius: 4px;
  font-family: Consolas, Monaco, monospace;
  font-size: 0.9em;
}
pre {
  padding: 10px 12px;
  border-left: 3px solid #3498db;
  overflow-x: auto;
  margin: 12px 0;
}
textarea {
  width: 100%;
  min-height: 130px;
  padding: 10px;
  border: 1px solid #ddd;
  resize: vertical;
  box-sizing: border-box;
}
.note {
  background-color: #fff8e1;
  border-left: 4px solid #ffc107;
  padding: 10px 12px;
  margin: 15px 0;
  border-radius: 0 4px 4px 0;
  font-size: 0.95em;
}
.tip {
  background-color: #e3f2fd;
  border-left: 4px solid #2196f3;
  padding: 10px 12px;
  margin: 10px 0;
  border-radius: 0 4px 4px 0;
  font-size: 0.95em;
}
.warning {
  background-color: #ffebee;
  border-left: 4px solid #e53935;
  padding: 10px 12px;
  margin: 10px 0;
  border-radius: 0 4px 4px 0;
  font-size: 0.95em;
}
a {
  color: #1976d2;
  text-decoration: none;
}
a:hover {
  text-decoration: underline;
}
.step {
  background-color: #ffffff;
  border-radius: 6px;
  padding: 10px 14px;
  margin: 12px 0;
  box-shadow: 0 1px 3px rgba(0,0,0,0.04);
}
.step-title {
  font-weight: bold;
  margin-bottom: 5px;
}
footer {
  margin: 40px 0 20px;
  text-align: center;
  color: #7f8c8d;
  font-size: 0.9em;
}
.highlight-box {
  border: 1px dashed #90caf9;
  background-color: #f1f8ff;
  padding: 8px 10px;
  border-radius: 4px;
  font-size: 0.9em;
  margin: 8px 0 4px;
}

/* ---------------- 左侧本章目录 ---------------- */
.chapter-nav {
  position: fixed;
  top: 20px;
  left: 20px;
  width: 200px;
  background: #2c3e50;
  padding: 16px 14px;
  border-radius: 6px;
  color: white;
  box-shadow: 0 3px 6px rgba(0,0,0,0.1);
}
.chapter-nav h3 {
  color: #ecf0f1;
  margin-top: 0;
  margin-bottom: 10px;
  font-size: 1em;
  font-weight: bold;
}
.chapter-nav a {
  display: block;
  padding: 6px 0;
  color: #ecf0f1;
  font-size: 0.92em;
}
.chapter-nav a:hover {
  background: rgba(255,255,255,0.1);
  padding-left: 6px;
}

/* ---------------- 复制按钮 ---------------- */
#copyBtn {
  float: right;
  margin-bottom: 6px;
  padding: 6px 12px;
  background:#3498db;
  color:white;
  border:none;
  border-radius:4px;
  cursor:pointer;
}
#copyBtn:hover {
  background:#217dbb;
}