SCSS Image Ratio

imageratio.scss

@function pxtoem($target, $context:16px) {
    @return ($target / $context) + 0em;
}

.entry-attachment { // Image ratio 135x180
    $w: 135px;
    $h: 180px;
    $ratio: 100/($w/$h);
    padding-top: $ratio;
    display: block;
    overflow: hidden;
    position: relative;
    width: pxtoem($w);
    height: pxtoem($h);
    background: url(images/logo.png) center center no-repeat; // Placeholder if no image
    background-size: 50%;

    img {
        display: block;
        min-width: 100%;
        min-height: 100%;
        position: absolute;
        top: 0;
        bottom: 0;
        left: 0;
        right: 0;
    }
}