wagtail/docs/_static/css/docsearch.overrides.css

.search .algolia-docsearch-suggestion--highlight,
.algolia-autocomplete .algolia-docsearch-suggestion--highlight {
  color: #2980B9;
  background: #F1C40F;
}

.algolia-autocomplete {
    width: 100%;
}

#search-results a,
a.algolia-docsearch-suggestion {
    border-bottom: 0;
}
#search-results  h2 {
    display: none;
}