:root {
  --bg: #ffffff;
  --fg: #111111;
  --muted: #666666;
  --border: #e5e5e5;
  --link: #0645ad;
}

* { box-sizing: border-box; }
html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.6;
}

a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }

.layout {
  display: flex;
  min-height: 100vh;
}

.sidebar {
  width: 220px;
  border-right: 1px solid var(--border);
  padding: 24px;
  position: sticky;
  top: 0;
  height: 100vh;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.brand {
  font-weight: 700;
  font-size: 20px;
  color: inherit;
  text-decoration: none;
}

.nav {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.nav a { color: inherit; }
.nav a.active, .nav a[aria-current="page"] { text-decoration: underline; font-weight: 600; }

.content {
  flex: 1;
  padding: 32px;
  display: flex;
  flex-direction: column;
}

.container {
  max-width: 760px;
}

.container p {
  text-align: justifys;
}

.acknowledgment {
  font-size: 0.9rem;
  color: var(--muted);
  font-style:italic;
  font-weight: 600;
}

.figure { margin: 20px 0; text-align: center; }
.figure img { width: auto; height: 480px; max-width: 100%; border-radius: 8px; display: inline-block; }
.figure figcaption { text-align: center; color: var(--muted); font-size: 0.9rem; margin-top: 8px; }

.footer {
  margin-top: auto;
  padding-top: 24px;
  border-top: 1px solid var(--border);
  color: var(--muted);
}

.meta { color: var(--muted); font-size: 0.95rem; }

h1, h2, h3 { line-height: 1.2; }
h1 { font-size: 28px; margin: 0 0 16px; }
p { margin: 0 0 12px; }

@media (max-width: 820px) {
  .layout { flex-direction: column; }
  .sidebar {
    width: 100%;
    height: auto;
    position: static;
    border-right: none;
    border-bottom: 1px solid var(--border);
    padding: 16px;
  }
  .nav { flex-direction: row; flex-wrap: wrap; gap: 12px 16px; }
  .content { padding: 20px; }
}