.blue-box {
    width: 500px;
    height: 500px;
    background-color: #4348ff;
    color: whitesmoke;
    font-weight: bold;
    padding: 10px;
    font-size: 20px;
}

.yellow-box {
    width: 200px;
    height: 200px;
    background-color: #ffcb48;
    color: #2a2a2a;
    font-weight: bold;
    padding: 10px;
    font-size: 20px;
}


.iframe {
    width: 100%;
    height: 500px;
    border: 3px solid #4348ff;
}

.iframe-holder:fullscreen {
    width: 100%;
    height: 100%;
}