Use any of the available button classes to quickly create a styled button.
Fancy larger or smaller buttons? Add .btn-lg, .btn-sm, or .btn-xs for additional sizes.
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Create block level buttons—those that span the full width of a parent— by adding .btn-block.
Buttons will appear pressed (with a darker background, darker border, and inset shadow) when active. For <button> elements, this is done via :active. For <a> elements, it's done with .active. However, you may use .active on <button>s should you need to replicate the active state programmatically.
No need to add :active as it's a pseudo-class, but if you need to force the same appearance, go ahead and add .active.
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Add the .active class to <a> buttons.
Make buttons look unclickable by fading them back 50%.
Add the disabled attribute to <button> buttons.
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If you add the disabled attribute to a <button>, Internet Explorer 9 and below will render text gray with a nasty text-shadow that we cannot fix.
Add the .disabled class to <a> buttons.
We use .disabled as a utility class here, similar to the common .active class, so no prefix is required.
This class uses pointer-events: none to try to disable the link functionality of <a>s, but that CSS property is not yet standardized and isn't fully supported in Opera 18 and below, or in Internet Explorer 11. So to be safe, use custom JavaScript to disable such links.
While button classes can be used on <a> and <button> elements, only <button> elements are supported within our nav and navbar components.
Use the button classes on an <a>, <button>, or <input> element.
As a best practice, we highly recommend using the <button> element whenever possible to ensure matching cross-browser rendering.
Among other things, there's a bug in Firefox <30 that prevents us from setting the line-height of <input>-based buttons, causing them to not exactly match the height of other buttons on Firefox.