signal-desktop/stylesheets/_lightbox.scss

.lightbox-container {
  display: none;
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: $z-index-modal;
}

.iconButton {
  // NOTE: Cannot move these to inline styles as hover breaks due to precedence.
  // We use vanilla CSS-in-JS which outputs inline styles. The `:hover`
  // pseudo-class cannot be expressed using vanilla CSS-in-JS, so we define it
  // here. If we move the other properties to JS, they have higher precedence
  // as they are inline and the `:hover` `background` change won’t override the
  // base `background` definition. Revisit this as we adopt a more sophisticated
  // style system in the future:
  background: transparent;
  width: 50px;
  height: 50px;

  display: inline-block;
  cursor: pointer;
  border-radius: 50%;
  padding: 3px;

  &:before {
    content: '';
    display: block;
    width: 100%;
    height: 100%;
  }

  &:hover {
    background: $grey;
  }

  &.save {
    &:before {
      @include color-svg('../images/save.svg', white);
    }
  }

  &.close {
    &:before {
      @include color-svg('../images/x.svg', white);
    }
  }

  &.previous {
    &:before {
      @include color-svg('../images/back.svg', white);
    }
  }

  &.next {
    &:before {
      @include color-svg('../images/forward.svg', white);
    }
  }
}