.checkmark-block-container {
    max-width: 800px !important;
    margin-left: auto;
    margin-right: auto;
    padding: 16px 16px 0px 16px;
    border-width: 1px;
    border-style: solid;
    margin: 16px 0 24px 0;
}
  
.block-editor-block-list__block .checkmark-block-container .block-editor-inner-blocks .block-editor-block-list__layout .block-editor-block-list__block {
    margin: 0;
  
}