editor.css

div#ks-editor section {
    border: 1px lightgrey solid;
    border-radius: 1px;
    margin: 5px;
    padding: 2.5px;
    width: auto;
}

div#ks-editor section > * {
    margin: 2.5px;
}

div#ks-editor *.selected {
    background-color: lightblue;
}