[Css] Icon Fonts: How do they work?


If your question is how a CSS class can insert a specific character (that will be rendered as an icon in the special font), take a look at the source for FontAwesome:

.icon-glass:before { content: "\f000"; }
.icon-music:before { content: "\f001"; }
.icon-search:before { content: "\f002"; }
.icon-envelope:before { content: "\f003"; }
.icon-heart:before { content: "\f004"; }

So a CSS content directive is used to insert the character (which is from a special private-use reserved area of Unicode that does not mess up other readers).


I understand that icon fonts are just fonts and that you can get the icons by just calling their classname, but how do icon fonts work?

I've tried checking the related icon font resources loaded in Chrome to see how icon fonts display icons (in comparison to general fonts) but I haven't been able to figure out how this happens.

I've also been unsuccessful in finding resources on how this "icon font technique" is done, even though there are loads of icon fonts available. There are also loads of resources showing how icon fonts can be integrated, but no one seems to be sharing or writing about how this is done!

A similar question was asked here Basically it's how, for example, font awesome works :

Actual font icons (FontAwesome, for instance) do involve downloading a specific font and make use of the content property. Here's an example of completely raw FontAwesome in use as a font, turning  ( - you may not be able to see this!) into an ambulance: http://jsfiddle.net/GWqcF/2

You can also look at how font awesome is implemented

Can I add color to bootstrap icons only using CSS?

Yes, if you use Font Awesome with Bootstrap! The icons are slightly different, but there are more of them, they look great at any size, and you can change the colors of them.

Basically the icons are fonts and you can change the color of them just with the CSS color property. Integration instructions are at the bottom of the page in the provided link.

Edit: Bootstrap 3.0.0 icons are now fonts!

As some other people have also mentioned with the release of Bootstrap 3.0.0, the default icon glyphs are now fonts like Font Awesome, and the color can be changed simply by changing the color CSS property. Changing the size can be done via font-size property.

How to display Unicode character in bootstrap 3?

You'll have to add the below line in your head tag and define the font-family wherever you use these unicode characters in your custom css file. Then only will you be able to see the desired icon.

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">

Refer this for more details.

Because the glyphicons are now fonts, one can use the contextual classes to apply the appropriate color to the icons.

For example: <span class="glyphicon glyphicon-info-sign text-info"></span> adding text-info to the css will make the icon the info blue color.