.listbox-area {
    display: grid;
    grid-gap: 2em;
    grid-template-columns: repeat(2, 1fr);
    padding: 20px;
    border: 1px solid #aaa;
    border-radius: 4px;
    background: #eee;
}

[role="listbox"] {
    margin: 1em 0 0;
    padding: 0;
    min-height: 18em;
    border: 1px solid #aaa;
    background: white;
}

[role="listbox"]#ss_elem_list {
    position: relative;
    max-height: 18em;
    overflow-y: auto;
}

[role="listbox"] + *,
.listbox-label + * {
    margin-top: 1em;
}

[role="group"] {
    margin: 0;
    padding: 0;
}

[role="group"] > [role="presentation"] {
    display: block;
    margin: 0;
    padding: 0 0.5em;
    font-weight: bold;
    line-height: 2;
    background-color: #ccc;
}

[role="option"] {
    position: relative;
    display: block;
    padding: 0 1em 0 1.5em;
    line-height: 1.8em;
}

[role="option"].focused {
    background: #bde4ff;
}

[role="option"][aria-selected="true"]::before {
    position: absolute;
    left: 0.5em;
    content: "✓";
}

button[aria-haspopup="listbox"] {
    position: relative;
    padding: 5px 10px;
    width: 150px;
    border-radius: 0;
    text-align: left;
}

button[aria-haspopup="listbox"]::after {
    position: absolute;
    right: 5px;
    top: 10px;
    width: 0;
    height: 0;
    border: 8px solid transparent;
    border-top-color: currentcolor;
    border-bottom: 0;
    content: "";
}

button[aria-haspopup="listbox"][aria-expanded="true"]::after {
    position: absolute;
    right: 5px;
    top: 10px;
    width: 0;
    height: 0;
    border: 8px solid transparent;
    border-top: 0;
    border-bottom-color: currentcolor;
    content: "";
}

button[aria-haspopup="listbox"] + [role="listbox"] {
    position: absolute;
    margin: 0;
    width: 9.5em;
    max-height: 10em;
    border-top: 0;
    overflow-y: auto;
}

[role="toolbar"] {
    display: flex;
}

[role="toolbar"] > * {
    border: 1px solid #aaa;
    background: #ccc;
}

[role="toolbar"] > [aria-disabled="false"]:focus {
    background-color: #eee;
}

button {
    font-size: inherit;
}

button[aria-disabled="true"] {
    opacity: 0.5;
}

.move-right-btn::after {
    content: " →";
}

.move-left-btn::before {
    content: "← ";
}

.annotate {
    color: #366ed4;
    font-style: italic;
}

.hidden {
    display: none;
}

.offscreen {
    position: absolute;
    width: 1px;
    height: 1px;
    overflow: hidden;
    clip: rect(1px 1px 1px 1px);
    clip: rect(1px, 1px, 1px, 1px);
    font-size: 14px;
    white-space: nowrap;
}