:root {
  font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: #172033;
  background: #eef3f8;
  font-synthesis: none;
}

* { box-sizing: border-box; }

body { margin: 0; min-height: 100vh; }

.contenedor {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 2rem 1rem;
}

.tarjeta {
  width: min(760px, 100%);
  background: #ffffff;
  border-radius: 1.25rem;
  padding: clamp(1.4rem, 4vw, 2.7rem);
  box-shadow: 0 1.4rem 3.5rem rgba(28, 51, 84, 0.13);
  border-top: 0.45rem solid #164a7b;
}

.etiqueta {
  margin: 0;
  color: #406384;
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1 { margin: 0.45rem 0 0.6rem; font-size: clamp(1.8rem, 5vw, 2.7rem); }
.introduccion { margin-top: 0; line-height: 1.65; color: #455469; }

.campos {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
  margin: 1.6rem 0;
}

label { display: grid; gap: 0.45rem; font-weight: 700; }
input {
  width: 100%;
  border: 1px solid #b9c6d3;
  border-radius: 0.65rem;
  padding: 0.8rem;
  font: inherit;
}
input:focus { outline: 3px solid rgba(22, 74, 123, 0.22); border-color: #164a7b; }

.acciones { display: flex; flex-wrap: wrap; gap: 0.75rem; }
button {
  border: 0;
  border-radius: 0.65rem;
  padding: 0.85rem 1.2rem;
  background: #164a7b;
  color: white;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
}
button:hover { filter: brightness(1.08); }
button.secundario { background: #dfe7ef; color: #24364a; }

.resultado, .error {
  margin-top: 1.3rem;
  border-radius: 0.75rem;
  padding: 1rem 1.1rem;
}
.resultado { background: #e9f7ee; border-left: 0.35rem solid #28834f; }
.resultado h2 { margin-top: 0; }
.resultado p:last-child { margin-bottom: 0; font-weight: 800; }
.error { background: #fff0f0; border-left: 0.35rem solid #b83a3a; color: #7b2020; }
footer { margin-top: 2rem; color: #69778a; font-size: 0.88rem; }

@media (max-width: 650px) {
  .campos { grid-template-columns: 1fr; }
  .acciones button { width: 100%; }
}