body {
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background: linear-gradient(135deg, #0f172a 0%, #1e1b4b 100%);
    color: #f8fafc;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    overflow: hidden;
}

.challenge-container {
    background: rgba(30, 41, 59, 0.7);
    border: 1px solid rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-radius: 24px;
    padding: 48px;
    width: 100%;
    max-width: 450px;
    text-align: center;
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.5), 0 10px 10px -5px rgba(0, 0, 0, 0.5);
    animation: fadeIn 0.6s ease-out;
}

.logo-wrapper {
    margin-bottom: 32px;
}

.shield-icon {
    font-size: 64px;
    color: #6366f1;
    filter: drop-shadow(0 0 15px rgba(99, 102, 241, 0.5));
    animation: pulse 2s infinite ease-in-out;
}

h1 {
    font-size: 24px;
    font-weight: 700;
    margin: 0 0 12px 0;
    letter-spacing: -0.5px;
    background: linear-gradient(to right, #ffffff, #c7d2fe);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

p {
    font-size: 15px;
    color: #94a3b8;
    line-height: 1.6;
    margin: 0 0 32px 0;
}

.spinner-wrapper {
    display: flex;
    justify-content: center;
    align-items: center;
    margin-bottom: 32px;
}

.spinner {
    width: 60px;
    height: 60px;
    border: 4px solid rgba(99, 102, 241, 0.1);
    border-top: 4px solid #6366f1;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    box-shadow: 0 0 15px rgba(99, 102, 241, 0.2);
}

.footer-text {
    font-size: 12px;
    color: #64748b;
    margin-top: 24px;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
        filter: drop-shadow(0 0 15px rgba(99, 102, 241, 0.5));
    }
    50% {
        transform: scale(1.05);
        filter: drop-shadow(0 0 25px rgba(99, 102, 241, 0.8));
    }
}

@keyframes spin {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}

/* Fallback button if JS is disabled/slow */
.btn-verify {
    background: linear-gradient(135deg, #4f46e5 0%, #3730a3 100%);
    border: none;
    color: white;
    padding: 12px 28px;
    font-size: 14px;
    font-weight: 600;
    border-radius: 12px;
    cursor: pointer;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.2), 0 2px 4px -1px rgba(0, 0, 0, 0.1);
    transition: all 0.2s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    display: none; /* Only show when JS fallback triggers */
}

.btn-verify:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 15px -3px rgba(99, 102, 241, 0.4);
}