CSS Flexbox Perfect Centering

.flex-container {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  padding: 20px;
  box-sizing: border-box;
}

.centered-content {
  background: white;
  padding: 2rem;
  border-radius: 12px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
  text-align: center;
  max-width: 400px;
  width: 100%;
}

.centered-content h2 {
  color: #333;
  margin-bottom: 1rem;
  font-size: 1.5rem;
}

.centered-content p {
  color: #666;
  margin-bottom: 1.5rem;
  line-height: 1.6;
}

.centered-content button {
  background: #667eea;
  color: white;
  border: none;
  padding: 12px 24px;
  border-radius: 6px;
  font-size: 1rem;
  cursor: pointer;
  transition: background 0.3s ease;
}

.centered-content button:hover {
  background: #5a6fd8;
}