:root {
    --primary-gradient: linear-gradient(135deg, #667eea, #764ba2);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Poppins', sans-serif;
}

/* 🌌 FONDO */
body {
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;

    background: url("img/fondo.jpg") no-repeat center center;
    background-size: cover;

    padding-top: 70px;   /* espacio navbar */
    padding-bottom: 50px; /* espacio footer */
}

/* oscurecer ligeramente */
body::before {
    content: "";
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.3);
    z-index: -1;
}

/* 🟣 NAVBAR */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    padding: 15px 30px;

    background: rgba(255,255,255,0.08);
    backdrop-filter: blur(15px);

    border-bottom: 1px solid rgba(255,255,255,0.2);

    z-index: 1000;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    color: #fff;
    font-size: 20px;
    font-weight: 600;
}

.nav-links {
    list-style: none;
    display: flex;
    gap: 20px;
}

.nav-links a {
    text-decoration: none;
    color: #fff;
    font-size: 14px;
    transition: 0.3s;
}

.nav-links a:hover {
    opacity: 0.7;
}

/* 💎 CONTENEDOR PRINCIPAL */
.container {
    position: relative;
    display: flex;
    gap: 40px;
    padding: 40px;

    width: 95%;
    max-width: 900px;

    background: rgba(255,255,255,0.08);
    backdrop-filter: blur(25px);
    -webkit-backdrop-filter: blur(25px);

    border-radius: 20px;
    border: 1px solid rgba(255,255,255,0.2);

    box-shadow:
        0 20px 60px rgba(0,0,0,0.6),
        inset 0 0 30px rgba(255,255,255,0.05);

    transition: transform 0.2s ease;
}

/* brillo dinámico */
.container::before {
    content: "";
    position: absolute;
    inset: 0;
    border-radius: 20px;
    background: linear-gradient(120deg, rgba(255,255,255,0.25), transparent);
    pointer-events: none;
}

/* 💳 TARJETA */
.card-container {
    perspective: 1200px;
    width: 350px;
    height: 220px;
    transition: transform 0.2s ease;
}

/* wrapper SOLO flip */
.card-wrapper {
    width: 100%;
    height: 100%;
    transform-style: preserve-3d;
    transition: transform 0.6s ease;
}

/* flip */
.card-wrapper.flip {
    transform: rotateY(180deg);
}

/* caras */
.card-face {
    position: absolute;
    width: 100%;
    height: 100%;
    border-radius: 16px;
    padding: 25px;
    backface-visibility: hidden;

    background: linear-gradient(
        135deg,
        rgba(255,255,255,0.2),
        rgba(255,255,255,0.05)
    );

    backdrop-filter: blur(15px);

    border: 1px solid rgba(255,255,255,0.3);

    box-shadow:
        0 20px 40px rgba(0,0,0,0.8),
        inset 0 0 15px rgba(255,255,255,0.05);

    color: white;
}

.card-back {
    transform: rotateY(180deg);
}

/* chip */
.chip {
    width: 50px;
    height: 35px;
    background: linear-gradient(135deg, #d4af37, #f2d06b);
    border-radius: 6px;
}

/* logo */
.card-logo {
    position: absolute;
    top: 25px;
    right: 25px;
    font-weight: bold;
}

/* número */
.card-number {
    margin-top: 20px;
    font-size: 22px;
    letter-spacing: 2px;
}

/* detalles */
.card-details {
    display: flex;
    justify-content: space-between;
    margin-top: 20px;
}

.label {
    font-size: 10px;
    opacity: 0.8;
}

.info {
    font-size: 14px;
}

/* BACK */
.magnetic-strip {
    width: 100%;
    height: 45px;
    background: #000;
    margin-top: 25px;
}

.signature-area {
    margin: 15px 0;
    height: 35px;
    background: #eee;
    display: flex;
    align-items: center;
    padding-left: 10px;
    color: #333;
}

.cvv-area {
    text-align: right;
}

.cvv-box {
    background: #fff;
    color: #333;
    padding: 5px 10px;
    display: inline-block;
    border-radius: 4px;
}

/* 🧾 FORM */
.checkout-form {
    width: 350px;
    color: white;
}

.checkout-form h2 {
    margin-bottom: 20px;
}

.input-group {
    margin-bottom: 15px;
    display: flex;
    flex-direction: column;
}

/* 🧊 INPUTS CRISTAL */
input, select {
    background: rgba(255,255,255,0.08);
    border: 1px solid rgba(255,255,255,0.3);
    padding: 12px;
    border-radius: 8px;
    color: #fff;

    backdrop-filter: blur(10px);
    transition: 0.3s;
}

input::placeholder {
    color: rgba(255,255,255,0.6);
}

input:focus, select:focus {
    background: rgba(255,255,255,0.2);
    border-color: rgba(255,255,255,0.8);
}

/* 🔥 FIX SELECT */
select {
    appearance: none;
    -webkit-appearance: none;
}

option {
    background: #1e1e2f;
    color: #fff;
}

/* layout */
.row {
    display: flex;
    gap: 15px;
}

.date-inputs {
    display: flex;
    gap: 10px;
}

/* botón */
.pay-btn {
    width: 100%;
    margin-top: 10px;
    padding: 14px;
    background: var(--primary-gradient);
    border: none;
    border-radius: 8px;
    color: #fff;
    font-weight: 600;
    cursor: pointer;

    transition: 0.3s;
}

.pay-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(118,75,162,0.4);
}

/* 🟣 FOOTER */
.footer {
    position: fixed;
    bottom: 0;
    width: 100%;
    text-align: center;
    padding: 10px;

    background: rgba(255,255,255,0.08);
    backdrop-filter: blur(15px);

    border-top: 1px solid rgba(255,255,255,0.2);

    color: #fff;
    font-size: 12px;
}

/* 📱 RESPONSIVE */
@media (max-width: 900px) {
    .container {
        flex-direction: column;
        align-items: center;
        padding: 20px;
    }

    .card-container,
    .checkout-form {
        width: 100%;
        max-width: 320px;
    }

    .row {
        flex-direction: column;
    }

    .nav-links {
        display: none;
    }
}