meta-lightbox/scss/meta-lightbox-theme.scss

$lightbox-link-hover-color: #007bff !default;
$lightbox-breakpoint: 576px !default;

.meta-lightbox-theme-default.meta-lightbox-overlay {
    background: #666;
    background: rgba(0, 0, 0, 0.6);
}

.meta-lightbox-theme-default .meta-lightbox-nav {
    top: 10%;
    width: 8%;
    height: 80%;
    background-repeat: no-repeat;
    background-position: 50% 50%;
    opacity: 0.5;
    color: #fff;
    font-size: 3em;
    text-decoration: none;
    text-shadow: 1px 1px 0 #000;

    .fa {
        position: absolute;
        top: 50%;
        left: 50%;
        margin-top: -1em;
        margin-left: -0.2em;
    }

    &:hover {
        color: $lightbox-link-hover-color;
        opacity: 1;
        background-color: rgba(0, 0, 0, 0.5);
    }
}

.meta-lightbox-theme-default .meta-lightbox-close {
    display: block;
    opacity: 0.5;
    color: #fff;
    text-decoration: none;
    font-size: 2em;
    text-shadow: 1px 1px 0 #000;
    text-align: center;
    width: 1.2em;
    height: 1.2em;

    &:focus {
        color: $lightbox-link-hover-color;
        opacity: 1;
        background-color: rgba(0, 0, 0, 0.5);
    }
}

.meta-lightbox-theme-default .meta-lightbox-title {
    background: #000;
    color: #fff;
    padding: 7px 15px;
}

.meta-lightbox-theme-default .meta-lightbox-ajax,
.meta-lightbox-theme-default .meta-lightbox-inline {
    background: #fff;
    padding: 2em;
    box-shadow: 0px 1px 1px rgba(0, 0, 0, 0.4);
}

@media (max-width: $lightbox-breakpoint) {
    .meta-lightbox-wrap {
        top: 5px !important;
        bottom: 5px;
        left: 5px;
        right: 5px;
    }

    .meta-lightbox-theme-default .meta-lightbox-nav {
        height: 100%;
        opacity: 1;
        font-size: 2em;

        .fa {
            margin-left: -.4em;
        }
    }

    .meta-lightbox-theme-default .meta-lightbox-close {
        opacity: 1;
    }
}