oliverdavies.uk/assets/less/components/talk/slides.less

.talk-slides {
    background: url('../../../images/loading.gif') center no-repeat;
    min-height: 275px;

    @screen md {
        & {
            min-height: 375px;
        }
    }

    @screen lg {
        & {
            min-height: 450px;
        }
    }

    @screen xl {
        & {
            min-height: 560px;
        }
    }
}