/* General styling */
body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #4facfe, #00f2fe);
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
  padding: 1rem;
  color: #333;
}

/* Card container */
.container {
  background: #fff;
  padding: 2rem 2.5rem;
  border-radius: 16px;
  box-shadow: 0px 10px 25px rgba(0, 0, 0, 0.2);
  text-align: center;
  max-width: 450px;
  width: 100%;
  animation: fadeIn 0.8s ease-in-out;
}

/* Title */
h1 {
  margin-bottom: 0.5rem;
  color: #222;
  font-size: 1.8rem;
}

.subtitle {
  font-size: 0.95rem;
  color: #666;
  margin-bottom: 1.5rem;
}

/* Input */
input {
  padding: 12px;
  font-size: 1rem;
  width: 100%;
  margin-bottom: 1rem;
  border: 2px solid #ddd;
  border-radius: 8px;
  outline: none;
  transition: 0.3s;
  box-sizing: border-box;
}

input:focus {
  border-color: #007BFF;
  box-shadow: 0 0 8px rgba(0, 123, 255, 0.3);
}

/* Button */
button {
  padding: 12px;
  font-size: 1rem;
  border: none;
  border-radius: 8px;
  background: #007BFF;
  color: #fff;
  cursor: pointer;
  width: 100%;
  transition: all 0.3s ease-in-out;
  box-sizing: border-box;
}

button:hover {
  background: #0056b3;
  transform: translateY(-2px);
  box-shadow: 0px 6px 12px rgba(0, 0, 0, 0.15);
}

/* Output */
#output {
  margin-top: 1.5rem;
  font-size: 1.4rem;
  font-weight: bold;
  min-height: 28px;
  padding: 0.5rem;
  border-radius: 6px;
  background: #f9f9f9;
  color: #111;
  transition: 0.3s ease-in-out;
  animation: fadeInUp 0.6s ease-in-out;
}

/* Animations */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(15px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Responsive */
@media (max-width: 600px) {
  .container {
    padding: 1.5rem;
  }
  h1 {
    font-size: 1.5rem;
  }
  #output {
    font-size: 1.2rem;
  }
}