themes/docsy/assets/scss/_drawio.scss

div.drawio {
    display: inline-block;
    position: relative;

    button {
        position: absolute;
        font-size: 0.8em;
        bottom: 5px;
        right: 5px;
        background-color: rgba($secondary, .8);
        color: $primary-light;
        padding: 0.4em 0.5em;
        display: none;
    }

    &:hover button {
        display: inline;
    }
} 

div.drawioframe {
    position: fixed;
    height: 100%;
    width: 100%;
    top: 0;
    left: 0px;
    z-index: 1000;
    background: #000b;
    border: 0;

    iframe {
        position: absolute;
        height: 90%;
        width: 90%;
        top: 5%;
        left: 5%;
        z-index: 1010;
    }
}