无法在bootstrap3上居中div-Unabletocenterdivonbootstrap3

10  

In order to center a block level element using margin: 0 auto; it must also have a width that is smaller than its containing block (for the auto value to make sense) - because #container is spanning the width of its parent (the ) there is simply no margin to distribute.

为了使用margin来居中块级元素：0 auto;它的宽度必须小于其包含的块（因为auto值才有意义） - 因为#container跨越其父级的宽度（），所以根本没有要分配的边距。

An alernative approach to margin: 0 auto; would be to set .btn-toolbar to inline-block and then centering it by adding text-align: center; to its containing block. You can apply the same concept to the second example:

保证金的一种方法：0自动;将.btn-toolbar设置为内联块，然后通过添加text-align：center来居中;到它的包含块。您可以将相同的概念应用于第二个示例：

http://fiddle.jshell.net/52VtD/94/

http://fiddle.jshell.net/52VtD/94/

4  

In this instance, margin:0 auto doesn't work because the width of the element is 100%. If you want it to work, you would have to set a width on the element:

在这种情况下，margin：0 auto不起作用，因为元素的宽度是100％。如果你想要它工作，你必须在元素上设置一个宽度：

.btn-toolbar {
    width: 50px;
    margin: 0px auto;
}

If you want to center the text and the button, you could add the class text-center to the parent element, in this case: .row. The styling of this class is simply text-align: center.

如果要将文本和按钮居中，可以将类text-center添加到父元素，在这种情况下：.row。这个类的样式只是text-align：center。

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EXAMPLE HERE

这里的例子

As @Adrift points out, it would be much more efficient to center the element by making it inline-block, as you can use text-align:center as opposed to margin:0 auto and avoid having to set a fixed width on the element. This will ensure that the element is centered regardless of its width. (example here) - don't forget you can just add the class text-center to the parent for centering.

正如@Adrift指出的那样，通过使其成为内联块来居中元素会更有效率，因为您可以使用text-align：center而不是margin：0 auto并避免必须在元素上设置固定宽度。这将确保元素无论宽度如何都居中。 （例如这里） - 不要忘记你可以将类文本中心添加到父级以进行居中。

It's also worth noting that inline/inline-block elements respect white-space in the markup, and thus generate space if present. If you want to remove this space, see this answer.

值得注意的是，内联/内联块元素尊重标记中的空白，因此如果存在则生成空间。如果要删除此空间，请参阅此答案。