Add Counter and Modify the Flex propriety:
flex-direction: column-reverse;
to flex-direction: row-reverse;

If you prefer one column reverse re-use my old CSS:
http://pastebin.com/F9rmaAHX

This style use the New CSS FLEXBOX function.

More info about Flexbox :
http://css-tricks.com/snippets/css/a-guide-to-flexbox/

. Tool to test your CSS3 Compatibility:
http://css3test.com/ :
This Online test checks which CSS3 features the browser recognizes, not whether they are implemented correctly.

. FlexBox is new for me , some infos about it :
1 - http://caniuse.com/flexbox :
Compatibility table for support of Flexible Box Layout Module in desktop and mobile browsers.
2 - http://www.alsacreations.com/tuto/lire/1493-css3-flexbox-layout-module.html
3 - http://weblog.bocoup.com/dive-into-flexbox/A Very good explanation !

. Several flexbox playgrounds available online for experimenting:
1 - http://the-echoplex.net/flexyboxes/
2 - http://demo.agektmr.com/flexbox/

http://demo.agektmr.com/flexbox/ :
Syntax Testing/Visualizer Tool by Eiji Kitamura:
cool demo page, where we can test flexbox online .
(work for Firefox 20.1 with the "layout.css.flexbox.enabled. " ) .
found here :
http://zomigi.com/blog/css3-layout/ :
"CSS3 Layout presentation at In Control Orlando" (other infos in it)"

Other sources interesting around latest CSS3 :
- http://www.stunningcss3.com/
(A Project-based Guide to the Latest in CSS :by Zoe Mickley Gillenwater )

Read other infos in http://forum.userstyles.org/discussion/35421/multi-column#Item_17


=======================
►► ====== USO :8080 or MIRROR ??? ======
"userscripts.org" is down.....

► Use now "userscripts-mirror.org" :
You can Use "userscripts-mirror.org", the Static Mirror Of userscripts.org :
https://greasyfork.org/scripts/2222-uso-mirror by trespassersW:
Useful GM when searching for script via google, this userscript Redirects userscripts.org links to userscripts-mirror.org , the Static Mirror Of userscripts.org .
Also redirects userscripts.org:8080 links (which stop to work now).

Another solution:
Here are new settings for USO Mirror:

- Include pattern: (.*?)s?\://(.*?)\buserscripts.org(\:8080)?\/(.*)
- Redirect to: $1://$2userscripts-mirror.org/$4

► To follow this userscripts.org story and found the last tweaks:
https://greasyfork.org/forum/discussion/150/userscripts-org-is-down-but#latest

============================

It's a part of my "Flickr WideScreen Collection".

▶ The First one:
http://freestyler.ws/style/45755/flickr-widescreen-allinone-total-no-gm-v-37

Add a Dark/Grey Style?.
Use my personal tweak (more Dark):
▶ http://freestyler.ws/style/42914/flickr-widescreen-dark-grey-v-37

The "Flickr WideScreen Collection" :

► http://freestyler.ws/style/86249/flickr-small-justified-compact-top-header-v-4(include in ALLinONE)
► http://freestyler.ws/style/90564/flickr-widescreen-photo-page-less-wide-v-1 (include in ALLinONE)
► http://freestyler.ws/style/75316/flickr-new-global-nav-bar-3-scripts-gm-v-5 (include in ALLinONE)

- For Flickr Userscripts (GM: cf greasemonkey):
► http://freestyler.ws/style/45662/flickr-widescreen-gm-commented-on-v-8
▶ http://freestyler.ws/style/62649/flickr-widescreen-gm-flickr-functional-suite
► http://freestyler.ws/style/75316/flickr-new-global-nav-bar-3-scripts-gm-v-5

- For Flickr Viewers :
► http://freestyler.ws/style/63209/flickr-widescreen-viewer-flickrhivemind-v-3
► http://freestyler.ws/style/56181/flickr-widescreen-viewer-dackr-v-6

These Styles are better with this Useful Addon/Script to preview thumbnail on hover:
▶
▶ "Splash Album Viewer Fixed" - AutoPager support(http://userscripts.org:8080/scripts/show/91220)