#transitionpage:before {
     content: ""; /* have some text here if u wanna */
}

#transitionpage {
    position: fixed;
    z-index: 1;
    display: block;
    width: 100vw;
    height: 100vh;
    top: 0;
    left: 0;
    background-color: white;
    color: black;
    opacity: 1;
    transition: opacity 0.2s ease, visibility 0.2s ease;
}

#transitionpage.hidden {
    opacity: 0;
    visibility: hidden;
}