* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: Arial, Helvetica, sans-serif;
    min-height: 100vh;
    background: linear-gradient(135deg, #0b0f19, #111827, #172033);
    color: #ffffff;
}

/* CONTENEDOR PRINCIPAL */
.contenedor {
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 50px 20px;
}

/* TARJETA */
.tarjeta {
    width: 100%;
    max-width: 620px;

    background: rgba(20, 27, 40, 0.97);

    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 20px;

    /* Espacio interno de todos los lados */
    padding: 55px 60px;

    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.45);
}

/* ENCABEZADO */
.encabezado {
    text-align: center;
    margin-bottom: 45px;
}

.encabezado h1 {
    font-size: 32px;
    letter-spacing: 3px;
    color: #38bdf8;
    margin-bottom: 14px;
}

.encabezado p {
    color: #94a3b8;
    font-size: 15px;
}

/* CADA CAMPO */
.campo {
    width: 100%;
    margin-bottom: 34px;
}

/* ETIQUETA */
.campo label {
    display: block;
    margin-bottom: 14px;

    font-size: 14px;
    font-weight: bold;
    color: #e2e8f0;
}

/* INPUT */
.campo input {
    display: block;

    width: 100%;
    height: 54px;

    padding: 0 18px;

    border: 1px solid #334155;
    border-radius: 10px;

    background: #0f172a;
    color: #ffffff;

    font-size: 15px;

    outline: none;

    transition: all 0.3s ease;
}

.campo input::placeholder {
    color: #64748b;
}

.campo input:focus {
    border-color: #38bdf8;

    box-shadow:
        0 0 0 4px rgba(56, 189, 248, 0.12);
}

/* FILA DNI + TELÉFONO */
.fila {
    display: grid;

    /* Dos columnas */
    grid-template-columns: 1fr 1fr;

    /* Separación horizontal */
    column-gap: 35px;

    /* Separación vertical */
    row-gap: 20px;

    width: 100%;
}

/* CAMPOS DENTRO DE LA FILA */
.fila .campo {
    width: 100%;
}

/* BOTÓN */
button {
    display: block;

    width: 100%;
    height: 54px;

    margin-top: 10px;

    border: none;
    border-radius: 10px;

    background: linear-gradient(
        135deg,
        #0284c7,
        #38bdf8
    );

    color: #ffffff;

    font-size: 16px;
    font-weight: bold;

    cursor: pointer;

    transition: all 0.3s ease;
}

button:hover {
    transform: translateY(-2px);

    box-shadow:
        0 8px 20px rgba(56, 189, 248, 0.25);
}

button:active {
    transform: translateY(0);
}

/* PIE */
.pie {
    text-align: center;
    margin-top: 35px;
}

.pie p {
    color: #64748b;
    font-size: 13px;
}

/* MENSAJE */
.mensaje {
    text-align: center;
}

.mensaje h1 {
    color: #38bdf8;
    margin-bottom: 20px;
}

.mensaje p {
    color: #cbd5e1;
    margin-bottom: 30px;
    line-height: 1.7;
}

/* BOTÓN VOLVER */
.boton {
    display: inline-block;

    padding: 14px 30px;

    background: #0284c7;
    color: white;

    text-decoration: none;

    border-radius: 9px;

    font-weight: bold;

    transition: 0.3s;
}

.boton:hover {
    background: #0369a1;
    transform: translateY(-2px);
}

/* =========================================
   TABLETS
   ========================================= */

@media (max-width: 700px) {

    .tarjeta {
        max-width: 560px;

        padding-left: 40px;
        padding-right: 40px;
    }

    .fila {
        column-gap: 25px;
    }
}

/* =========================================
   CELULARES
   ========================================= */

@media (max-width: 600px) {

    .contenedor {
        padding: 30px 15px;
    }

    .tarjeta {
        padding: 35px 25px;
    }

    .encabezado {
        margin-bottom: 38px;
    }

    .encabezado h1 {
        font-size: 27px;
    }

    /* DNI y teléfono pasan a una sola columna */
    .fila {
        display: block;
    }

    .fila .campo {
        margin-bottom: 34px;
    }

    .campo {
        margin-bottom: 30px;
    }
}