Extra configuration options: Rounded corners, shadow, border, emphasize on hover.

Configuration

At admin/config/media/flickr in the section STYLING (CSS RELATED):

Use flickr.css

Checkbox.
Uncheck to take care of the styling yourself in custom CSS.
If you use Flickr Filter, you might find the AutoFloat module useful.

Image styles

Checkboxes.
- Rounded corners
- Shadow
- Border

Apply the image style also on the caption?

Radio buttons.
- No
- Yes, separate from the image
- Yes, wrapped around the image and caption ("Polaroid" effect if applied with a border)

Disable the above styles on a caption with only the text 'Flickr' (simple link)

Checkbox.

Emphasize the image on hover?

Radio buttons.
- No
- Enlarge slightly (includes the caption)
- Enlarge (image only) (*)
- Zoom (*)
- Magnifier icon
(*): The 'Zoom' and 'Enlarge' styles use bigger images to maintain the resolution. This has a slight performance impact and the size 'big square' (q) is not square but 150px on the longest side to avoid distortion on older browsers.

Suppress Flickr block titles

You can suppress the block titles with CSS. For example for the block 'Flickr: User photos with specific tags' ($delta=11), it would look like:

#block-flickr-11 .flickr-album-heading {
  display: none;
}

Image & album HTML structure

See https://www.drupal.org/node/2289797.

Do It Yourself

If you prefer to define all CSS yourself, read the instructions that explain how to make it look fancy in custom CSS. The results are similar to those of the Flickr Style sub-module that obviously is less error prone. Furthermore the sub-module makes it easier to switch between one style and another to make the end client choose their preference.