.upgrade-overlay {
    position: fixed;
    top: 0; left: 0; width: 100vw; height: 100vh;
    z-index: 2000;
    display: flex;
    align-items: center;
    justify-content: center;
}
.upgrade-dialog {
    background: #fff;
    border-radius: 8px;
    box-shadow: 0 4px 32px rgba(0,0,0,0.15);
    padding: 2rem;
    min-width: 320px;
    max-width: 90vw;
    z-index: 2010;
    position: relative;
}
.upgrade-backdrop {
    position: fixed;
    top: 0; left: 0; width: 100vw; height: 100vh;
    background: rgba(0,0,0,0.25);
    z-index: 2005;
}