.block-editor-iframe__body .is-root-container section.section {
    height: 80px;
    border: 1px solid #000;
    overflow: hidden;
    position: relative;
}
.block-editor-iframe__body .is-root-container section.section::before {
    z-index: 1;
    content: "click to edit";
    top: 0;
    position: absolute;
    width: 100%;
    height: 100%;
    align-content: center;
    text-align: center;
    font-family: sans-serif;
    font-size: 18px;
    background: #fff;
}
.block-editor-block-list__layout .block-editor-block-list__block::before {
    content: attr(data-title);
    width: 100%;
    height: 100%;
    align-content: center;
    text-align: center;
    font-family: sans-serif;
    font-size: 18px;
    background: #000;
    display: block;
    color: #fff;
    padding: 10px;
    box-sizing: border-box;
}