Add arrow controls

stylesheets/_lightbox.scss

@@ -42,4 +42,16 @@
       @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);
+    }
+  }
 }

ts/components/Lightbox.tsx

@@ -43,7 +43,7 @@ const styles = {
 };
 
 interface IconButtonProps {
-  type: 'save' | 'close';
+  type: 'save' | 'close' | 'previous' | 'next';
   onClick?: () => void;
 }
 const IconButton = ({ onClick, type }: IconButtonProps) => (
@@ -71,6 +71,8 @@ export class Lightbox extends React.Component<Props, {}> {
         <div style={styles.controls}>
           <IconButton type="close" onClick={this.props.close} />
           <IconButton type="save" onClick={this.props.save} />
+          <IconButton type="previous" />
+          <IconButton type="next" />
         </div>
       </div>
     );