.editor {
    border: 1px solid #aaa;
    border-radius: 4px;
    padding: .5em .5em 0;
    background-color: #F3F4F5;
}

.summary {
    font-weight: bold;
    margin: -.5em -.5em 0;
    padding: .5em;
}

.editor[open] {
    padding: .5em;
}

.editor[open] summary {
    border-bottom: 1px solid #aaa;
    margin-bottom: .5em;
}