Everybody likes to make their blog reflect themselves as much as possible. For most of us, this is hard, since we are not PHP programmers and can’t really afford to pay someone to design a custom theme just for us. Fortunately there are a lot of people and companies out there that are willing to design all kinds of themes they make available for free, either for advertising or just to share their creation. This wide choice of themes allows you to find something close to what you want. And the plugin developers have been busy designing ways for you to tweak things to make them even closer to your desire.
Custom User CSS allows you to add custom CSS styling to your theme. Basically, after installing and activating the plugin, you go to the option page (Under Settings rather than under Appearance. Seems off to me.) and type in the CSS you want to add. It will override the styling already included in a theme, so you can change just about anything you want.
Of course, this is only true if you know two things. First, the names of the classes and ids you want to change, and second, how to style with CSS. The first part is easy with the plugins that tell you what tags they use, or allow you to set your own. Figuring out which ones to use in a theme to get the effect you want is more difficult. The second problem is much harder to overcome.
It is easy to decide who should be downloading this plugin. For the average user, this plugin is pretty much worthless. For those like me that are more familiar with CSS and comfortable with looking at page sources to find tags, this is very handy for tweaking styling.
Style Tweaker is pretty much the same plugin as the Custom User plugin. You activate it, go to the options page, under Appearance this time, and enter your CSS. So it has the same strengths and liabilities as the other plugin. But it also adds a couple of nice options in that make it a more versatile plugin, especially for multi-user blogs.
One the options page there are 3 places to input CSS code. The first is private, the only one that will see them is the current user, in the theme they are currently using. This is great for working with styling without worrying about what your visitors see. The second box will show up for anyone looking at your blog with the current theme, the third will show for anyone, in any theme they are using.
The third option is pretty much just for multi-user blogs, but the first two are very nice for anyone that wants to tweak their sites without worrying about what they are showing their visitors. And it is much easier than setting up and maintaining a second blog for testing stuff.
WP Post Styling give you exact control over the styling of each individual post and page on your blog. It adds a window on your post and page editing pages where you can put in any styling you want for that particular page. The CSS is placed in a custom field, so it only shows up in the header of that page when it is looked at.
The option page allows you to toggle whether the plugin is on or off by default, the size of the editing box, and exactly what kind of styles will be added to a page, mobile, screen, or print. This means you can create suitable looks for your pages even if your theme does not support mobile or print styles.
The same kind of limitations apply here as the other plugins. You need to already know CSS for it to be useful. If you do know CSS, it allows a great deal of customization for your posts and pages. You can have a different style for each post in a series, or for each author on a multi-author blog.
For the rest
All of the plugins so far have required a knowledge of CSS and finding out specific tags in your stylesheets in order to make changes. Although useful, this has limited their utility for most people who do not have that kind of knowledge. Theme Tweaker is for those users.
After activation, you go to the Theme Tweaker options page under Appearance, where you will be presented 2 lists of colors. At first, both are all the colors that the plugin found in your theme. One is Read-Only, and it will remain there so you know where you started. The other can be changed, either selectively using a very nice color picker, or all at once using the 5 preset buttons on the page. After making your changes, you can choose to make them visible only to Administrators or to all visitors.
When you have finalized your choices, you have 3 options, leave the settings as they are on the options page until you want to make more changes, download a generated stylesheet you can upload to the theme directory to replace the original, or generate a Child theme that you upload to a different directory. The first choice allows you to easily make any changes you want at any time, without removing your original theme colors. The second completely removes the old colors and replaces them unless you save a copy of the original stylesheet. The third means you can easily update your theme, without having to worry about losing your style changes.
There are some limits to what you can do. The plugin will only pick up colors in your main theme stylesheet, so if you have a separate one for widgets, you will have to change them manually. Unless it is obvious, i.e., you know your background color is white, you will not know exactly what you are changing with your tweaks. If two different tags use the same color, both elements will change, there is no way to limit it to just one tag. While the directions are pretty good, a clearer explanation of how to use a child theme could be useful for those not familiar with them.
But the problems with the plugin are very minor. Easy to install and use, allowing the user to decide exactly how much effort he wants to go through for his changes, and does what it is supposed to. All the things that help make a very good plugin. If you want make those small changes that will really make your blog yours, but you don’t know programming, this is the way to do it.
All of these are easy to install, but their ease of use depends on your own skills at working with CSS. Which one you chose will depend on exactly what you want to do and how comfortable you are with CSS programming. But if you are not a programmer, and just want to get the colors of your new theme jsut right, there is only the one choice.