Bootstrap按钮类

<!-- Standard button -->
<button type = "button" class = "btn btn-default">Default Button</button>

<!-- Provides extra visual weight and identifies the primary action in a set of buttons -->
<button type = "button" class = "btn btn-primary">Primary Button</button>

<!-- Indicates a successful or positive action -->
<button type = "button" class = "btn btn-success">Success Button</button>

<!-- Contextual button for informational alert messages -->
<button type = "button" class = "btn btn-info">Info Button</button>

<!-- Indicates caution should be taken with this action -->
<button type = "button" class = "btn btn-warning">Warning Button</button>

<!-- Indicates a dangerous or potentially negative action -->
<button type = "button" class = "btn btn-danger">Danger Button</button>

<!-- Deemphasize a button by making it look like a link while maintaining button behavior -->
<button type = "button" class = "btn btn-link">Link Button</button>