* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  font-family: system-ui, -apple-system, sans-serif;
  background: #f5f5f5;
}

.contenedor {
  background: #fff;
  padding: 2rem;
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
  max-width: 360px;
  width: 100%;
}

h1 {
  margin: 0 0 1.5rem 0;
  font-size: 1.5rem;
  color: #333;
}

.formulario {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.formulario label {
  font-weight: 500;
  color: #444;
}

.formulario input {
  padding: 0.6rem 0.75rem;
  border: 1px solid #ccc;
  border-radius: 6px;
  font-size: 1rem;
}

.formulario input:focus {
  outline: none;
  border-color: #555;
  box-shadow: 0 0 0 2px rgba(0, 0, 0, 0.06);
}

.formulario button {
  padding: 0.65rem 1rem;
  background: #333;
  color: #fff;
  border: none;
  border-radius: 6px;
  font-size: 1rem;
  cursor: pointer;
  margin-top: 0.25rem;
}

.formulario button:hover {
  background: #222;
}

.resultado {
  margin-top: 1.25rem;
  padding: 0.75rem 1rem;
  min-height: 2.5rem;
  border-radius: 6px;
  background: #f8f8f8;
  border: 1px solid #eee;
  color: #333;
  font-size: 1rem;
}

.resultado.vacio {
  color: #888;
}

.resultado.error {
  background: #fef2f2;
  border-color: #fecaca;
  color: #991b1b;
}