hightlight search results wp

function search_excerpt_highlight() {
    $excerpt = get_the_excerpt();
    $keys = implode('|', explode(' ', get_search_query()));
    $excerpt = preg_replace('/(' . $keys .')/iu', '<strong class="search-highlight">\0</strong>', $excerpt);

    echo '<p>' . $excerpt . '</p>';
}

function search_title_highlight() {
    $title = get_the_title();
    $keys = implode('|', explode(' ', get_search_query()));
    $title = preg_replace('/(' . $keys .')/iu', '<strong class="search-highlight">\0</strong>', $title);

    echo $title;
}

search.css

.search-highlight {
   color: #fa0;
}

search.php

<?php echo apply_filters('the_title', search_title_highlight() ); ?>

<?php echo apply_filters('the_excerpt', search_excerpt_highlight() ); ?>