:root {
    color-scheme: light;
    font-family: Inter, "Segoe UI", sans-serif;
    color: #182230;
    background: #f3f6fb;
}

* { box-sizing: border-box; }

body {
    min-height: 100vh;
    margin: 0;
    display: grid;
    place-items: center;
    padding: 24px;
    background: radial-gradient(circle at top left, #e0eaff, transparent 42%), #f3f6fb;
}

.tarjeta {
    width: min(100%, 560px);
    padding: 42px;
    background: #fff;
    border: 1px solid #e4eaf2;
    border-radius: 20px;
    box-shadow: 0 20px 60px #243b5320;
}

.etiqueta {
    color: #5267d8;
    font-size: .78rem;
    font-weight: 700;
    letter-spacing: .09em;
    text-transform: uppercase;
}

h1 { margin: 14px 0 10px; font-size: clamp(2rem, 7vw, 3rem); }
.intro, .nota { color: #667085; line-height: 1.65; }
form { margin-top: 28px; }
label { display: block; margin-bottom: 9px; font-weight: 600; }
.fila-formulario { display: flex; gap: 10px; }
input, button { min-height: 48px; border-radius: 10px; font: inherit; }
input { min-width: 0; flex: 1; padding: 0 14px; border: 1px solid #d0d5dd; outline: none; }
input:focus { border-color: #5267d8; box-shadow: 0 0 0 3px #5267d822; }
button { padding: 0 18px; border: 0; background: #5267d8; color: white; font-weight: 650; cursor: pointer; }
button:hover { background: #4053bd; }
.respuesta { padding: 13px 15px; border-radius: 10px; background: #ecfdf3; color: #067647; line-height: 1.5; }
.boton-secundario { margin-top: 22px; background: #eef1ff; color: #4053bd; }
.boton-secundario:hover { background: #e1e6ff; }
.nota { margin: 18px 0 0; font-size: .9rem; }

body.tema-oscuro { color: #eff2ff; background: radial-gradient(circle at top left, #28345e, transparent 42%), #111827; }
.tema-oscuro .tarjeta { background: #1f2937; border-color: #344054; }
.tema-oscuro .intro, .tema-oscuro .nota { color: #b8c1d1; }
.tema-oscuro input { color: #eff2ff; background: #182230; border-color: #475467; }

@media (max-width: 480px) {
    .tarjeta { padding: 28px 22px; }
    .fila-formulario { flex-direction: column; }
}