* { box-sizing: border-box; }
body {
  font-family: system-ui, sans-serif;
  margin: 0;
  background: #f5f5f5;
  color: #1a1a2e;
  display: flex;
}
.sidebar {
  width: 220px;
  min-height: 100vh;
  background: #1a1a2e;
  color: #fff;
  flex-shrink: 0;
  display: flex;
  flex-direction: column;
}
.brand {
  padding: 20px;
  font-size: 20px;
  font-weight: bold;
  border-bottom: 1px solid #333;
}
.nav { display: flex; flex-direction: column; padding: 12px 0; flex: 1; }
.nav-item { padding: 12px 20px; color: #ccc; text-decoration: none; }
.nav-item:hover { background: #16213e; color: #fff; }
.nav-item.active { background: #0f3460; color: #fff; border-left: 3px solid #fff; }
.logout-btn {
  margin: 16px;
  padding: 8px;
  background: transparent;
  color: #ccc;
  border: 1px solid #444;
  border-radius: 4px;
  cursor: pointer;
}
.logout-btn:hover { background: #16213e; color: #fff; }
.content { flex: 1; padding: 20px; }
.panel { background: #fff; padding: 16px; margin-bottom: 16px; border-radius: 8px; }
h2 { font-size: 16px; margin-top: 0; }
input {
  display: block;
  padding: 8px;
  margin: 8px 0;
  width: 100%;
  max-width: 320px;
  border: 1px solid #ccc;
  border-radius: 4px;
}
.actions { margin: 12px 0; }
button {
  background: #0f3460;
  color: #fff;
  border: none;
  padding: 8px 16px;
  border-radius: 4px;
  cursor: pointer;
  margin-right: 8px;
}
button:hover { background: #16213e; }
button:disabled { background: #999; cursor: not-allowed; }
.tip { font-size: 13px; color: #666; margin: 8px 0; }