discourse/app/assets/stylesheets/common/base/lightbox.scss

.lightbox {
  position: relative;
  display: inline-block;

  &:hover .meta {
    opacity: 0.9;
    transition: opacity 0.5s;
  }
}

.lightbox-wrapper {
  display: inline-block;
  &,
  * {
    outline: 0;
  }
}

.meta {
  position: absolute;
  bottom: 0;
  width: 100%;
  color: $secondary;
  background: $primary;
  opacity: 0;
  transition: opacity 0.2s;

  span {
    float: left;
  }

  .filename {
    margin: 6px 6px 2px 6px;
    max-width: 100%;
    overflow: hidden;
    white-space: nowrap;
    text-overflow: ellipsis;
    &:before {
      font-family: "FontAwesome";
      content: "\F03E";
      margin-right: 5px;
    }
  }

  .informations {
    margin: 6px;
    padding-right: 20px;
    color: $secondary-high;
    font-size: $font-0;
  }

  .expand {
    position: absolute;
    bottom: 4px;
    right: 7px;
    &:before {
      font-family: "FontAwesome";
      content: "\F065";
    }
  }
}