src/doc/theme/cargo.css

dd > p {
    /* For loose definitions that have a p tag inside, don't add a bunch of
    space before the definition. This can removed after updating to mdbook 0.5. */
    margin-top: 0;
}

/* Override mdbook's link color for option links. */
a.option-anchor, a.option-anchor > * {
    color: var(--fg) !important;
}