base.css

/* popup, tab, options, help */

:root {
    --border-radius: 8px; /* Matches FF popup's rounded corners */

    --popup-button-size: 30px;
    --popup-row-height: 36px;
    --popup-name-height: 28px;
    --popup-name-width: 20rem;
    --popup-field-x-padding: 6px;
    --popup-heading-height: 22px;
    --popup-private-button-color: darkorchid;
    --danger-color: red;
    --success-color: #0b0;

    --accent-color: #0061e0;
    --text-color: black;
    --muted-text-color: #666;
    --private-text-color: purple;
    --samp-text-color: #ddd;
    --page-bg-color: white;
    --popup-field-color: white;
    --popup-row-color: #eee;
    --popup-hover-row-color: #ddd;
    --popup-border-color: #ccc;
    --popup-hover-button-color: #ccc;
}

.dark {
    --accent-color: #0df;
    --text-color: white;
    --muted-text-color: #ccc;
    --private-text-color: #f6f;
    --samp-text-color: #33333b;
    --page-bg-color: #23222b;
    --popup-field-color: #23222b;
    --popup-row-color: #42414d;
    --popup-hover-row-color: #52525e;
    --popup-border-color: #333;
    --popup-hover-button-color: #666;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
    accent-color: var(--accent-color);
}

hr {
    border-width: .5px;
    opacity: .5;
}

a {
    color: var(--accent-color);
}

kbd {
    padding: 0 3px;
    border: 1px solid currentColor;
    border-radius: 3px;
}

samp {
    font-size: 1rem;
    font-weight: bold;
    white-space: nowrap;
    background-color: var(--samp-text-color);
}

.error {
    border-color: var(--danger-color) !important;
}