Astra Portfolio: Styling - Screenshot - http://tinyurl.com/yc9kbzkh

styling.css

/**
 * Styling the WP Portfolio grid.
 *
 * 1. Filters - Category & Other Category
 * 2. Single Portfolio Item
 * 3. Quick View
 * 4. Portfolio Title
 */

/**
 * 1. Filters - Category & Other Category
 */

/** Filter background */
.astra-portfolio-wrap .astra-portfolio-filters {
    background: #3b3e46;
}

/** Filter link */
.astra-portfolio-wrap .filter-links li a {
    color: #fff;
}

/** Filter active link */
.astra-portfolio-wrap .filter-links li .active {
    color: #03A9F4;
}

/**
 * 2. Single Portfolio Item
 */

/** Single Portfolio */
.astra-portfolio-wrap .site-single .inner {
    border: 5px solid #03A9F4;
}

/** Hover on Single Portfolio */
.astra-portfolio-wrap .site-single:hover .view-demo-wrap {
    background: rgba(255, 255, 255, 0.6784313725490196);
}

/**
 * 3. Quick View
 */

/** Quick view */
.astra-portfolio-wrap .view-demo {
    background: #33a9f4;
    color: #fff;
    border-radius: 20px;
}

/** Hover on Quick view */
.astra-portfolio-wrap .view-demo:hover {
    box-shadow: 0 0 3px 3px rgba(0, 0, 0, 0.23);
}

/**
 * 4. Portfolio Title
 */
.astra-portfolio-wrap .template-meta {
    background: #33a9f4;
    color: #fff;
}