* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: Arial, sans-serif;
  display: flex;
  height: 100vh;
  background-color: #f4f6f9;
}

.sidebar {
  width: 200px;
  background: #1e2a38;
  color: white;
  display: flex;
  flex-direction: column;
  padding: 20px 10px;
}

.sidebar .logo {
  text-align: center;
  margin-bottom: 30px;
}

.sidebar .logo img {
  width: 60px;
}

.sidebar ul {
  list-style: none;
}

.sidebar ul li {
  padding: 12px;
  cursor: pointer;
  border-radius: 6px;
  margin-bottom: 10px;
}

.sidebar ul li.active,
.sidebar ul li:hover {
  background: #007bff;
}

.main {
  flex: 1;
  display: flex;
  flex-direction: column;
  padding: 20px;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

header h1 {
  font-size: 24px;
}

.status {
  font-weight: bold;
}

.status.online {
  color: green;
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px;
}

.card {
  background: white;
  padding: 20px;
  border-radius: 10px;
  box-shadow: 0px 4px 6px rgba(0,0,0,0.1);
  text-align: center;
}

.card h3 {
  margin-bottom: 10px;
}

.value {
  font-size: 28px;
  font-weight: bold;
  color: #007bff;
}

button {
  padding: 10px 20px;
  border: none;
  border-radius: 6px;
  background: red;
  color: white;
  font-weight: bold;
  cursor: pointer;
}

button.on {
  background: green;
}

.chart-card {
  grid-column: span 2;
}