{exp:low_search:form result_page="searchtest/results" form_id="beersearch"}
    <fieldset>
        <p>
            {exp:channel:categories category_group="2" style="linear"}
                <label>
                    <input type="checkbox" name="category:type[]" value="{category_id}"{if low_search_category:type ~ '/\b'.category_id.'\b/'} checked{/if}>
                    {category_name}
                </label>
            {/exp:channel:categories}
        </p>
        <p>
            {exp:channel:categories category_group="1" style="linear"}
                <label>
                    <input type="checkbox" name="category:style[]" value="{category_id}"{if low_search_category:style ~ '/\b'.category_id.'\b/'} checked{/if}>
                    {category_name}
                </label>
            {/exp:channel:categories}
        </p>

        <p><button id="submit">Search</button></p>
    </fieldset>
{/exp:low_search:form}

{exp:low_search:results
    query="{segment_3}"
    limit="500"
    orderby_sort="title|desc"
    require_all="category:type|category:style"
}
    ...
{/exp:low_search:results}