body {
  margin: 0;
  font-family: Arial, sans-serif;
  background: linear-gradient(135deg,#6f7bd9,#7e5ac8);
  color: #333;
}

.header {
  text-align: center;
  color: #fff;
  padding: 30px 10px;
}

.nav {
  display: flex;
  justify-content: center;
  background: rgba(255,255,255,0.15);
}

.nav a {
  color: #eee;
  padding: 15px 25px;
  text-decoration: none;
}

.nav a.active {
  background: #fff;
  color: #333;
  border-radius: 6px 6px 0 0;
}

.container {
  padding: 30px;
  display: grid;
  grid-template-columns: repeat(3,1fr);
  gap: 20px;
}

.card {
  background: #fff;
  border-radius: 12px;
  padding: 20px;
}

.grid {
  display: grid;
  grid-template-columns: repeat(2,1fr);
  gap: 15px;
  text-align: center;
}

button {
  margin-top: 10px;
  padding: 8px 15px;
  border: none;
  border-radius: 6px;
  background: #4a7cff;
  color: #fff;
  cursor: pointer;
}

pre {
  background: #111;
  color: #0f0;
  padding: 10px;
  border-radius: 6px;
  height: 120px;
  overflow: auto;
}

.checklist {
  list-style: none;
  padding: 0;
}

.ok { color: green; }