:root {
  --primary-blue: #1a3a8a;
  --accent-blue: #2563eb;  
  --bg-white: #f8fafc;    
  --text-dark: #1e293b;    
}

body {
  font-family: 'Inter', sans-serif;
  background-color: var(--bg-white);
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
  color: var(--text-dark);
}

.app-container {
  background: #ffffff;
  width: 100%;
  max-width: 400px;
  padding: 40px;
  border-radius: 24px;
  box-shadow: 0 4px 6px -1px rgba(26, 58, 138, 0.1), 
              0 20px 25px -5px rgba(26, 58, 138, 0.1);
  text-align: center;
}

.header h1 {
  font-weight: 700;
  margin: 0 0 8px 0;
  color: var(--primary-blue);
  letter-spacing: -0.025em;
}

.header p {
  color: #64748b;
  font-size: 0.9rem;
  margin-bottom: 32px;
}

.input-section {
  text-align: left;
  margin-bottom: 24px;
}

.input-section label {
  display: block;
  font-weight: 600;
  font-size: 0.85rem;
  margin-bottom: 8px;
  color: var(--primary-blue);
}

input[type="date"] {
  width: 100%;
  padding: 12px 16px;
  border: 2px solid #e2e8f0;
  border-radius: 12px;
  font-family: inherit;
  font-size: 1rem;
  color: var(--text-dark);
  transition: all 0.3s ease;
  box-sizing: border-box;
}

input[type="date"]:focus {
  outline: none;
  border-color: var(--accent-blue);
  box-shadow: 0 0 0 4px rgba(37, 99, 235, 0.1);
}

button {
  width: 100%;
  background-color: var(--primary-blue);
  color: white;
  padding: 14px;
  border: none;
  border-radius: 12px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.3s ease;
}

button:hover {
  background-color: var(--accent-blue);
}

.result-area {
  margin-top: 20px;
  padding-top: 10px;
  border-top: 1px solid #f1f5f9;
}

.age-number {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--primary-blue);
  display: block;
}

.age-label {
  font-size: 0.9rem;
  color: #64748b;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.placeholder-text {
  color: #94a3b8;
  font-style: italic;
}