.checkout-backdrop {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.7);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.checkout-backdrop.is-visible {
    display: flex;
}

.checkout-modal {
    background: #111;
    border: 1px solid var(--color-border);
    border-radius: 12px;
    padding: 2rem 2.5rem;
    width: min(520px, 90vw);
    text-align: center;
    box-shadow: 0 10px 40px rgba(0,0,0,0.5);
}

.checkout-modal h3 {
    margin-bottom: 0.75rem;
}

.checkout-modal p {
    margin-bottom: 1.5rem;
}

.checkout-sub { opacity: .7; font-size: .9rem; }

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid rgba(255,255,255,0.15);
    border-top-color: #9b59b6;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 1rem auto;
}

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

.checkout-close {
    position: absolute;
    right: 1rem;
    bottom: 1rem;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}