* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    Helvetica, Arial, sans-serif;
}

body {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #121c34;
  color: #e5e7eb;
}

.app {
  width: 100%;
  padding: 1rem;
  display: flex;
  justify-content: center;
}

.card {
  width: 360px;
  padding: 2rem;
  border-radius: 16px;
  background: #111827;
  border: 1px solid #1f2933;
  box-shadow: 0 20px 30px rgba(0, 0, 0, 0.45);
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.card-header {
  text-align: center;
}

.card-header h1 {
  font-size: 1.5rem;
  font-weight: 600;
  color: #f9fafb;
}

.card-header p {
  font-size: 0.875rem;
  color: #9ca3af;
  margin-top: 0.25rem;
}

.inputs {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
}

.input-group {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.input-group label {
  font-size: 0.8rem;
  font-weight: 500;
  color: #9ca3af;
}

.input-group input {
  padding: 0.65rem 0.75rem;
  border-radius: 8px;
  font-size: 0.95rem;
  border: 1px solid #374151;
  background: #020617;
  color: #f9fafb;
  outline: none;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.input-group input::placeholder {
  color: #6b7280;
}

.input-group input:focus {
  border-color: #2563eb;
  box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.35);
}

.convert-btn {
  margin-top: 0.5rem;
  padding: 0.7rem;
  border-radius: 10px;
  border: none;
  background: #2563eb;
  color: #ffffff;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s ease, transform 0.15s ease, box-shadow 0.15s ease;
}

.convert-btn:hover {
  background: #1d4ed8;
  transform: translateY(-1px);
  box-shadow: 0 8px 16px rgba(37, 100, 235, 0.351);
}

.convert-btn:active {
  transform: translateY(0);
  box-shadow: none;
}