After downloading a complete pack of bootstrap 3 from http://getbootstrap.com, I noticed that there is a separate css file for theme. How to make use of it? Please explain?
I included bootstrap-theme.css in my existing bootstrap project, but there is no difference in output.
Upon downloading Bootstrap 3.x, you'll get bootstrap.css and bootstrap-theme.css (not to mention the minified versions of these files that are also present).
bootstrap.css is completely styled and ready to use, if such is your desire. It is perhaps a bit plain but it is ready and it is there.
You do not need to use bootstrap-theme.css if you don't want to and things will be just fine.
bootstrap-theme.css is just what the name of the file is trying to suggest: it is a theme for bootstrap that is creatively considered 'THE bootstrap theme'. The name of the file confuses things just a bit since the base bootstrap.css already has styling applied and I, for one, would consider those styles to be the default. But that conclusion is apparently incorrect in light of things said in the Bootstrap documentation's examples section in regard to this bootstrap-theme.css file:
"Load the optional Bootstrap theme for a visually enhanced experience."
The above quote is found here http://getbootstrap.com/getting-started/#examples on a thumbnail that links to this example page http://getbootstrap.com/examples/theme/. The idea is that bootstrap-theme.css is THE bootstrap theme AND it's optional.
About the themes at BootSwatch.com: These themes are not implemented like bootstrap-theme.css. The BootSwatch themes are modified versions of the original bootstrap.css. So, you should definitely NOT use a theme from BootSwatch AND the bootstrap-theme.css file at the same time.
About Your Own Custom Theme: You might choose to modify bootstrap-theme.css when creating your own theme. Doing so may make it easier to make styling changes without accidentally breaking any of that built-in Bootstrap goodness.
For an example of the css styles have a look at: http://getbootstrap.com/examples/theme/
If you want to see how the example looks without the bootstrap-theme.css file open up your browser developer tools and delete the link from the <head> of the example and then you can compare it.
I know this is an old question but posted it just in case anyone is looking for an example of how it looks like I was.
Update
bootstrap.css = main css framework (grids, basic styles, etc)
bootstrap-theme.css = extended styling (3D buttons, gradients etc). This file is optional and does not effect the functionality of bootstrap at all, it only enhances the appearance.
Update 2
With the release of v3.2.0 Bootstrap have added an option to view the theme css on the doc pages. If you go to one of the doc pages (css, components, javascript) you should see a "Preview theme" link at the bottom of the side nav which you can use to turn the theme css on and off.
First, bootstrap-theme.css is nothing else but equivalent of Bootstrap 2.x style in Bootstrap 3. If you really want to use it, just add it ALONG with bootstrap.css (minified version will work too).
Bootstrap-theme.css is the additional CSS file, which is optional for you to use. It gives 3D effects on the buttons and some other elements.
As stated by others, the filename bootstrap-theme.css is very confusing. I would have chosen something like bootstrap-3d.css or bootstrap-fancy.css which would be more descriptive of what it actually does. What the world sees as a "Bootstrap Theme" is a thing you can get from BootSwatch which is a totally different beast.
With that said, the effects are quite nice - gradients and shadows and such. Unfortunately this file will wreak havoc on BootSwatch Themes, so I decided to dig into what it would take to make it play nice with them.
Bootstrap-theme.css is generated from the theme.less file in the Bootstrap source. The affected elements are (as of Bootstrap v3.2.0):
The theme.less file depends on:
@import "variables.less";
@import "mixins.less";
The code uses colors defined in variables.less in several places, for example:
// Give the progress background some depth
.progress {
#gradient > .vertical(@start-color: darken(@progress-bg, 4%); @end-color: @progress-bg)
}
This why bootstrap-theme.css totally messes up BootSwatch Themes. The good news is that BootSwatch Themes are also created from variables.less files, so you can simply build a bootstrap-theme.css for your BootSwatch Theme.
The right way to do it is to update the Theme build process, but here here is the quick and dirty way. Replace the variables.less file in the Bootstrap source with the one from your Bootswatch Theme and build it and voila you have a bootstrap-theme.css file for your Bootswatch Theme.
Building Bootstrap may sound daunting, but it is actually very simple:
Done. See, that was easy, wasn't it?
I know this post is kinda old but...
As 'witttness' pointed out.
About Your Own Custom Theme You might choose to modify bootstrap-theme.css when creating your own theme. Doing so may make it easier to make styling changes without accidentally breaking any of that built-in Bootstrap goodness.
I see it as Bootstrap has seen over the years that everyone wants something a bit different than the core styles. While you could modify bootstrap.css it might break things and it could make updating to a newer version a real pain and time consuming. Downloading from a 'theme' site means you have to wait on if that creator updates that theme, big if sometimes, right?
Some build their own 'custom.css' file and that's ok, but if you use 'bootstrap-theme.css' a lot of stuff is already built and this allows you to roll your own theme faster 'without' disrupting the core of bootstrap.css. I for one don't like the 3D buttons and gradients most of the time, so change them using bootstrap-theme.css. Add margins or padding, change the radius to your buttons, and so on...