body {
  font-family: 'Segoe UI', Arial, sans-serif;
  background: #f7f7f7;
  color: #222;
  margin: 0;
  padding: 0;
}
.cover {
  background: linear-gradient(120deg, #1e3c72, #2a5298);
  color: #fff;
  text-align: center;
  padding: 40px 20px 20px 20px;
}
.cover-img {
  width: 180px;
  height: 240px;
  object-fit: cover;
  border-radius: 12px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.2);
  margin-bottom: 20px;
}
h1 {
  font-size: 2.5em;
  margin: 0.2em 0 0.1em 0;
}
h2 {
  margin-top: 1.5em;
  color: #1e3c72;
}
.intro, .toc {
  background: #fff;
  margin: 30px auto;
  max-width: 700px;
  border-radius: 10px;
  box-shadow: 0 2px 8px rgba(30,60,114,0.08);
  padding: 24px 32px;
}
.toc ol {
  padding-left: 1.2em;
}
.toc a {
  color: #2a5298;
  text-decoration: none;
  transition: color 0.2s;
}
.toc a:hover {
  color: #e67e22;
}
footer {
  text-align: center;
  margin: 40px 0 20px 0;
  color: #888;
}
footer a {
  color: #1e3c72;
  text-decoration: none;
  font-weight: bold;
}
footer a:hover {
  color: #e67e22;
}
@media (max-width: 600px) {
  .intro, .toc {
    padding: 16px 8px;
  }
  .cover-img {
    width: 120px;
    height: 160px;
  }
  h1 {
    font-size: 1.5em;
  }
}