.fullscreen {
    position: relative;
    z-index: 9999;
}

.fullscreen .container {
    opacity: 0;
    pointer-events: none;
}
.fullscreen .container.show {
    opacity: 1;
}
.fullscreen .container.show > * {
    pointer-events: auto;
}

fullscreen-mask {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background-color: var(--allpage-bg-color);
    opacity: 0;
    cursor: pointer;
    pointer-events: none;
    transition: opacity .3s .15s;
}
fullscreen-mask.show {
    opacity: .6;
    pointer-events: auto;
}