.sidebar {
  min-width: 220px;
  max-width: 250px;
  min-height: calc(100vh - 56px); /* 56px header */
  border-right: 1px solid #e0e0e0;
}
.sidebar .nav-link {
  color: #333;
  font-weight: 500;
  transition: background 0.2s;
  border-radius: 0.35rem;
}
.sidebar .nav-link.active,
.sidebar .nav-link:hover {
  background: #e6f0ff;
  color: #0070f3;
}
header img {
  background: #fff;
  border-radius: 8px;
  padding: 2px 6px;
}
body {
  background: #f8fafc;
}
main {
  background: #fff;
  border-radius: 0.5rem;
  box-shadow: 0 2px 12px rgba(0,0,0,0.04);
  min-height: 600px;
}