from posting by Raphael Nikolai
The Problem:
Your post images does not align properly. May it be left, right or centered, it never aligns as it should be.
Cause:
This is an issue with your wordpress theme. The css styles that your current theme is using is incorrect or conflicting.
The Blog Fix:
The WordPress WYSIWYG editor automatically generates global/universal classes for each image alignment style that you desire. These CSS classes should be properly declared on your CSS stylesheet.
WordPress Global/Universal Image Classes:
/*global/universal image classes */
img.alignleft, img.left { float: left; }
img.alignright, img.right { float: right; }
img.aligncenter, img.center { display: block; margin-right: auto; margin-left: auto; float: none; clear: both; }
img.alignnone, img.block { display: block; clear: both; }
img.frame { background: #eee; border-style: solid; border-color: #ddd; }
img.stack { clear: none !important; }
img[align=”left”] { float: left; clear: left; }
img[align=”right”] { float: right; clear: right; }
img[align=”middle”] { display: block; margin-right: auto; margin-left: auto; float: none; clear: both; }/*—:[ image captioning ]:—*/
.wp-caption { border-style: solid; border-color: #ddd; background-color: #eee; text-align: center; font-style: italic; }
.wp-caption.alignleft { float: left; }
.wp-caption.alignright { float: right; }
.wp-caption.aligncenter { margin-right: auto; margin-left: auto; float: none; clear: both; }
.wp-caption.alignnone { clear: both; }/*global/universal image classes */
I should work automatically after copying and pasting the CSS code above. You can edit the colors on each class if you want to customize how your images are displayed.
If still centering does not work, then look for conflicting img class in your css (hint: use CTRL F and look for for “ img { ” or “ img{ “). If you find one then delete the margin set on that img class – centered images are displayed in blocks and margins should be set to automatic, that is why there should be no global margins set on your images. If it is possible, delete all other properties like padding, border, etc.