.cover-slider__wrap {
    position: relative;
    max-width: 640px;
    height: 480px;
    margin: 2em auto;
    padding: 5em 1em;
    color: #fff;
    line-height: 2;
    font-family: 'Trebuchet MS', sans-serif;
    font-weight: bold;
    box-shadow: 0 0 .5em rgba(#000,.5);
}
.cover-slider__inner {
    position: relative;
    min-height: 40em;
    text-align: center;
    z-index: 10;
}
.cover-slider {
    backface-visibility: hidden;
}
.cover-slider__slide {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 100%;
    padding: 0;
    margin: 0;
    background-size: cover;
    background-position: center;
    list-style: none;
    z-index: 0;
    opacity: .5;
    &.active {
        animation-duration: 2500ms;
        animation-name: slidein;
        animation-fill-mode: forwards;
    }
    &.inactive {
        animation-duration: 2500ms;
        animation-name: slideout;
        animation-fill-mode: forwards;
    }
    @keyframes slidein {
        from {
            left: 0;
            right: 100%;
        }
        to {
            left: 0;
            right: 0;
        }
    }
    @keyframes slideout {
        from {
            left: 0;
            right: 0;
        }
        to {
            left: 100%;
            right: 0;
        }
    }
}
// EXTRA STUFF
// these will unfortunately be inline
// in the final product
.cover-slider__slide {
    &:nth-child(1){
        background-image: url("https://placeimg.com/640/480/arch/grayscale");
    }
    &:nth-child(2){
        background-image: url("https://placeimg.com/640/480/nature/grayscale");
    }
    &:nth-child(3){
        background-image: url("https://placeimg.com/640/480/animals/grayscale");
    }
    &:nth-child(4){
        background-image: url("https://placeimg.com/640/480/people/grayscale");
    }
}
body {
    background: teal;
    box-sizing: border-box;
}
*, *:before, *:after {
    box-sizing: inherit;
}
.hide {
    position: absolute;
    left: -9999px;
}