body {
}
```css
body {
  font-family: system-ui, -apple-system, sans-serif;
  margin: 0;
  color: #1f2937;
  background: #f9fafb;
}

header {
  background: #0f172a;
  color: white;
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

nav a {
  color: white;
  margin-left: 20px;
  text-decoration: none;
  font-weight: 500;
}

.hero {
  padding: 100px 20px;
  text-align: center;
  background: linear-gradient(135deg,#0f172a,#1e3a8a);
  color: white;
}

.container {
  max-width: 1100px;
  margin: auto;
  padding: 40px 20px;
}

.card {
  background: white;
  padding: 25px;
  border-radius: 12px;
  box-shadow: 0 10px 25px rgba(0,0,0,0.05);
  margin-bottom: 20px;
}

footer {
  background: #0f172a;
  color: white;
  text-align: center;
  padding: 20px;
}

button {
  background: #2563eb;
  color: white;
  border: none;
  padding: 12px 20px;
  border-radius: 8px;
  cursor: pointer;
}

input, textarea {
  width: 100%;
  padding: 12px;
  margin: 10px 0;
  border-radius: 6px;
  border: 1px solid #ccc;
}

/* ============================= */
/* RESPONSIVE DESIGN */
/* ============================= */

@media (max-width: 768px) {

  header {
    flex-direction: column;
    align-items: flex-start;
  }

  nav {
    margin-top: 10px;
  }

  nav a {
    margin: 8px 10px 0 0;
    display: inline-block;
  }

  .hero {
    padding: 60px 15px;
  }

  .hero h1 {
    font-size: 1.8rem;
  }

  .container {
    padding: 25px 15px;
  }

  .card {
    padding: 20px;
  }
}