body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  margin: 0;
  background: #f5faff;
  color: #1a1a1a;
}
header {
  text-align: center;
  padding: 2rem 1rem;
  background: #eaf3ff;
}
header img {
  width: 100px;
  border-radius: 8px;
}
header h1 {
  font-size: 2rem;
  margin: 1rem 0 0.25rem;
  color: #0b3d91;
}
header p {
  color: #365eaa;
  margin: 0.25rem 0;
}
main {
  max-width: 1200px;
  margin: 2rem auto;
  padding: 0 1rem;
}
details {
  background: white;
  border-radius: 12px;
  margin-bottom: 1.5rem;
  padding: 1.2rem 1.5rem;
  box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}
details[open] section {
  max-height: 600px;
  overflow-y: auto;
  padding-right: 1rem;
}
summary {
  font-size: 1.3rem;
  font-weight: 700;
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  color: #0b3d91;
}
summary::before {
  content: url('data:image/svg+xml;utf8,<svg fill="%230b3d91" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><path d="M12 2l7 13H5l7-13zm0 4.3L8.05 13h7.9L12 6.3z"/></svg>');
  display: inline-block;
  width: 20px;
  height: 20px;
  margin-right: 0.5rem;
}
summary::-webkit-details-marker {
  display: none;
}
summary::after {
  content: '\25BC';
  margin-left: auto;
  transition: transform 0.3s ease;
}
details[open] summary::after {
  transform: rotate(180deg);
}
section h2 {
  font-size: 1.3rem;
  color: #0b3d91;
  margin: 1rem 0 0.5rem;
}
section h3 {
  font-size: 1.15rem;
  color: #2b5dab;
  margin-top: 2rem;
  border-top: 1px solid #ddd;
  padding-top: 1rem;
}
section h4 {
  font-size: 1.05rem;
  color: #4a78c2;
  font-style: italic;
  margin-top: 0.75rem;
}
section p, section ul {
  font-size: 1rem;
  color: #333;
  line-height: 1.6;
  margin-bottom: 1rem;
}
footer {
  background: #eaf3ff;
  color: #0b3d91;
  text-align: center;
  padding: 1rem;
  font-size: 0.95rem;
  margin-top: 3rem;
}
a {
  color: #0b3d91;
  text-decoration: underline;
}
.toc {
  background: #f0f7ff;
  border: 1px solid #d0e4ff;
  padding: 0.5rem 1rem;
  margin-bottom: 1rem;
  border-radius: 8px;
}
.toc ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}
.toc li a {
  color: #0b3d91;
  text-decoration: none;
  font-weight: 500;
}
.toggle-btn {
  background-color: #0b3d91;
  color: white;
  padding: 0.5rem 1rem;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  margin-bottom: 1rem;
}
.toggle-btn:hover {
  background-color: #06326e;
}