How to change the woocommerce price filter color

I believe you need to change the border and the background like this:

.woocommerce .widget_price_filter .price_slider_wrapper .ui-widget-content {
border: 2px solid #1ab2ff;
}

span.ui-slider-handle.ui-state-default.ui-corner-all {
background: #0088cc;
border: 1px solid #0088cc;
}

for custom themes it can be different.