.lightbox {
    display: none; /* Hidden by default */
    position: fixed; /* Stay in place */
    z-index: 1; /* Sit on top */
    left: 0;
    top: 0;
    width: 100%; /* Full width */
    height: 100%; /* Full height */
    overflow: auto; /* Enable scroll if needed */
    background-color: rgb(0,0,0); /* Fallback color */
    background-color: rgba(0,0,0,0.9); /* Black w/ opacity */
}

.lightbox-content {
    position: relative;
    top: 15%;
    width: 60%; /* Could be more or less, depending on screen size */
    margin: auto;
    padding: 20px;
    border: 1px solid #888;
    background: #fefefe;
}

.close-btn {
    color: #aaa;
    position: absolute;
    top: 10px;
    right: 25px;
    font-size: 35px;
    font-weight: bold;
}

    .close-btn:hover,
    .close-btn:focus {
        color: black;
        text-decoration: none;
        cursor: pointer;
    }

iframe {
    width: 100%;
    height: 400px; /* Adjust as necessary */
}