▶ NEW DESIGN Oct 2013 (after the last of dec 2012) :
Use :
http://freestyler.ws/style/80156/yahoo-new-mail-simply-dark-and-gray-v-35

▶ Use it with the "Dark Official Them of Yahoo Mail"....
I haven't tested with their others colors.

▶ WORK IN PROGRESS....
PARTICULARITY :
- HEADER: more compact, Reduce/Move elements, Supp Yahoo Logo, tiny Search Box etc...
- YAHOO SERVICES ICON : Not near The Reception Tab,
move to the Top/right of Search Block (like that we don't open always this yahoo popup )
- MENUS : More Infos in it , less scrolling... and Dark Gray, style Background/Border/separator, Hover etc ...
- LEFT PANEL : Custom Panels LIST Scrollable to just move it without move the entire page,
(when i want put a mail in a special folder by example)
> APPLICATIONS PANEL : Styled
- CONTACTS : More readable, without the White Column on the right("theAd" !)
- CONTACTS EDITION : More readable and wide place to type your infos
- MAILS LIST : ZEBRA List, Icons readability/usability(Background), MAILS style for hover/Read/selected,
- MAILS LIST : TRASH Icon (move near OBJECT and STAR icon and replaced by a "X")

- MAIL READ/WRITE : Color , Wide Place to play(to read/write), wide contacts box, Color picker style
- MAIL WRITE (Choose CONTACT BOX) : Wide "Choose a Contact list"
- MAIL READ / WRITE Readability/usability : add intern scrollbar to scroll only the mail , not all the page.
- Supp Publicity Column (Right Side Column : ("theAd" !))
- Supp White Space Under Message List


- TEST : support for the Preview under the messages list panel too
(without blank /white area around the toolbar).


▶ My ScreenShots are a little bit different than the results for this New Interface.
But they give a good idea of the style....

▶ For Slims and Dark ScrollBars in it, i use and RECOMMAND :

▷ http://freestyler.ws/style/124176/scrollbars-slim-arrowless

And you can test to :

▷ http://freestyler.ws/style/101886/fx-scrollbars-adjustments

You need to change the Background color for a darker cursor.

Like that :


/* === SLIM DARK SCROLLBAR (for MY USERSTYLE DARK/GRAY ==== */
scrollbarbutton {
-moz-appearance: none !important;
background-color: transparent !important;
border: none}

thumb {
-moz-appearance: none !important;
border: none !important;

/* == Tweak : background-color : CURSOR COLOR DARK (#999) == */
background-color: #999 !important;

border-radius: 10px !important;
box-shadow: inset 0 0 3px #000
}



▶ You can Use too , if you don't like publicity like me :

This Greasemonkey Script :
▷ http://userscripts.org/scripts/show/3115
It removes the ads + expands space .
Code uses Yahoo Mail's code and by that you will never need to update it...

You can use too :
▷
or
▷ :
Remove Ads In Gmail, Ymail, And Hotmail
================

▶ Thanks to:
- "New Yahoo! Mail Dark" ( http://freestyler.ws/style/40154/new-yahoo-mail-dark )
- "New Yahoo Mail clean up Userstyles" (http://freestyler.ws/style/33337/yahoo-mail-clean-up)
- "Yahoo! Mail - Black and wide" (http://freestyler.ws/style/47479/yahoo-mail-black-and-wide)