Hello!
First of all, thanks you for this plugin: it’s quite what I needed.

I would like to customize the appearance of checkboxes, so that those on this page look like those of this one.

I imagine this is a small setting to make in the style.css file, but I can not find which one. Could you give me a hand?

If it helps, I use this theme and here is my css code:

.searchandfilter ul {
	padding: 0px;
	-webkit-columns: 200px 3;
	-moz-columns: 200px 3;
	columns: 200px 3;
	text-align: right;
	column-gap: 40px;
}

.searchandfilter > ul > li {
	padding: 2px 0;
}

.searchandfilter .checkboxes {
    position: relative;
    padding-left: 30px;
    margin-bottom: 5px;
    cursor: pointer;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

.searchandfilter .checkboxes input {
    position: absolute;
    opacity: 0;
    cursor: pointer;
}

.searchandfilter .checkmark {
    position: absolute;
    top: 4px;
    left: 2px;
    height: 16px;
    width: 16px;
    background-color: #eee;
    border-radius: 4px;
}

.searchandfilter .checkboxes:hover input ~ .checkmark {
    background-color: #f8f8f8;
}

.searchandfilter .checkboxes input:checked ~ .checkmark {
    background-color: transparent;
}

.searchandfilter .checkmark:after {
    content: "";
    position: absolute;
    display: none;
}

.searchandfilter .checkboxes input:checked ~ .checkmark:after {
    display: block;
}

.searchandfilter .checkboxes .checkmark:after {
    left: 5px;
    top: -3px;
    width: 9px;
    height: 17px;
    border: solid #5EB28F;
    border-width: 0 3px 3px 0;
    -webkit-transform: rotate(45deg);
    -ms-transform: rotate(45deg);
    transform: rotate(45deg);
}

.searchandfilter .count {
    font-weight: normal;
    font-size: smaller;
    color: #888888;
}

And:

<div class="searchandfilter">
<ul><li><label class="checkboxes">One <span class="count">(1)</span><input type="checkbox" checked="checked"><span class="checkmark"></span></label></li>
<li><label class="checkboxes">Two <span class="count">(2)</span><input type="checkbox"><span class="checkmark"></span></label></li>
<li><label class="checkboxes">Three <span class="count">(3)</span><input type="checkbox"><span class="checkmark"></span></label></li>
<li><label class="checkboxes">Four <span class="count">(4)</span><input type="checkbox"><span class="checkmark"></span></label></li>
<li><label class="checkboxes">Five <span class="count">(5)</span><input type="checkbox"><span class="checkmark"></span></label></li>
<li><label class="checkboxes">Six <span class="count">(6)</span><input type="checkbox"><span class="checkmark"></span></label></li>
<li><label class="checkboxes">Seven <span class="count">(7)</span><input type="checkbox"><span class="checkmark"></span></label></li>
<li><label class="checkboxes">Eight <span class="count">(8)</span><input type="checkbox"><span class="checkmark"></span></label></li>
<li><label class="checkboxes">Nine <span class="count">(9)</span><input type="checkbox"><span class="checkmark"></span></label></li>
<li><label class="checkboxes">Ten <span class="count">(10)</span><input type="checkbox"><span class="checkmark"></span></label></li>
<li><label class="checkboxes">Eleven <span class="count">(11)</span><input type="checkbox"><span class="checkmark"></span></label></li>
<li><label class="checkboxes">Twelve <span class="count">(12)</span><input type="checkbox"><span class="checkmark"></span></label></li>
<li><label class="checkboxes">Thirteen <span class="count">(13)</span><input type="checkbox"><span class="checkmark"></span></label></li>
<li><label class="checkboxes">Fourteen <span class="count">(14)</span><input type="checkbox"><span class="checkmark"></span></label></li>
<li><label class="checkboxes">Fifteen <span class="count">(15)</span><input type="checkbox"><span class="checkmark"></span></label></li>
</ul>
</div>

Thanks!