If my style doesn't suffice as an ad hider, I recommend http://freestyler.ws/style/20041/pixiv for what probably is the ultimate Pixiv clutter killer.
Try out my other Pixiv style as well - http://freestyler.ws/style/31030/pixiv-net-compact-header.
Gray Grey Blue darken dark

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2014-09-30

• Colored background and controls @ RTL Manga pages

2014-06-23

• Fixed various link colors.
• Removed legacy support of -moz prefixed box-shadow and border-radius properties
• Code formatting.

2013-10-18

• Styled the "Read More" button on long descriptions

2013-10-07

• Styled the new configuration dropdown menu.
• Fixed the load more button @ illust. recommend pages.

2013-07-30

• Removed Suggested User box at home page
• Added attempt to remove premium promotion box at illust. pages.
• Added negative text-indent to magnifying glass to hide text
• Code maintenance: change few element selectors to lowercase.

2013-04-23

• Repaired buttons and other miscellany.

2012-12-13

• Remove new tag styling, recolored works page container.

2012-10-03

• Fixed the tag area at illust. pages.
• Added some basic support for Google Chrome, for objects that use gradients.

2012-05-29

• Added .premium to things to be removed
• Removed huge advertisement when not logged in
• Some other stuff I forget.

2012-05-19

• Colored Manga controls, pop-up menus.

2012-04-20

• Styled ASIDE elements at homepage.

2012-04-11

• Fix simple mistake (used #contents instead of #page-group #contents)

2012-04-08

• Styled page @ groups.
• Removed (all?) features requiring Premium subscription.

2012-03-30

• Removed "New" captions seen throughout website
• fixed some width misalignment issues.

2012-01-24

• Covered attach sample pop-up
• trying out a different way to hide left area ads based on #touch_introduction - Consequently removed some code.

2011-11-18

• Minor fixes.

2011-11-16

• More styling. Oh yeah, I can feel the bloat now.

2011-11-15

• Updated to fix new notification area.

2011-11-14

• Pixiv changed class names, updated.

2011-10-17

• Styling of novel items.
• If you want to remove Halloween logo insert #logoMap {display: none }

2011-09-29

• Mypage fixes.

2011-09-06

• Various fixes.

2011-09-01

• Set opacity: 1 to fix "hidden" image thumbnails when using AutoPager. For your AutoPager rule, Under Advanced > Lazy load image src attribute, set value to "data-src" without quotes.