:root {
    --brand-blue: #25aae2;
    --gold-primary: #ca8a04;
    --gold-light: #fde047;
}

body {
    background-color: var(--brand-blue);
    background-image: linear-gradient(135deg, #1aafee 0%, #c7e8f7 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    margin: 0;
    padding: 20px;
}

.premium-card {
    background: rgba(255, 255, 255, 0.98);
    border-radius: 30px;
    border: 4px solid var(--gold-primary);
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    position: relative;
    overflow: hidden;
    width: 100%;
    max-width: 420px;
}

/* HIỆU ỨNG SHIMMER */
.premium-card::before {
    content: "";
    position: absolute;
    top: 0;
    left: -150%;
    width: 80%;
    height: 100%;
    background: linear-gradient(to right, transparent, rgba(255, 255, 255, 0.6), transparent);
    transform: skewX(-25deg);
    animation: smoothShimmer 7s cubic-bezier(0.4, 0, 0.2, 1) infinite;
    pointer-events: none;
}

@keyframes smoothShimmer {
    0% { left: -150%; }
    20% { left: 150%; }
    100% { left: 150%; }
}

.btn-gold {
    background: linear-gradient(to bottom, var(--gold-light), var(--gold-primary));
    border-bottom: 4px solid #854d0e;
    color: #000;
    font-weight: 800;
    transition: all 0.2s ease;
    text-transform: uppercase;
}

.btn-gold:hover {
    filter: brightness(1.1);
    transform: translateY(-2px);
}

.btn-gold:active {
    transform: translateY(2px);
    border-bottom-width: 0;
}

.input-group {
    background: #f1f5f9;
    border: 2px solid #e2e8f0;
    transition: all 0.3s ease;
}

.input-group:focus-within {
    border-color: var(--brand-blue);
    background: #fff;
    box-shadow: 0 0 0 4px rgba(37, 170, 226, 0.1);
}

.gold-icon { color: var(--gold-primary); }
.blue-icon { color: var(--brand-blue); }

/* POPUP CAPTCHA */
#captcha-popup {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.85);
    backdrop-filter: blur(8px);
    z-index: 100;
    align-items: center;
    justify-content: center;
}

.popup-content {
    background: white;
    padding: 2rem;
    border-radius: 20px;
    border: 2px solid var(--brand-blue);
    text-align: center;
    box-shadow: 0 0 30px rgba(37, 170, 226, 0.4);
}