Bootstrap 4 center-block unable to center

问题

I have the following bootstrap html code (its JSX hence the className but the idea is the same):

<div className="toggleView btn-group center-block" role="group" aria-label="Basic example">
        <button onClick={this.handleTimelineClick} type="button" className={this.state.toggleCalendar == false ? "btn btn-secondary active" : "btn btn-secondary"}>Timeline</button>
        <button onClick={this.handleCalendarClick} type="button" className={this.state.toggleCalendar == true ? "btn btn-secondary active " :"btn btn-secondary"}>Calendar</button>
 </div>

I am trying to center this code with either bootstrap center-block or with CSS but cannot seem to get it to work:

The green bar highlights the div toggleView.

The only css I am using is the following:

.toggleView {
    padding: 20px;
}

Why can I not center this button group?

回答1:

btn-group has display:inline-block so you would use text-center in the parent container..

http://codeply.com/go/hyUYkUrtRN

NOTE: In Bootstrap 4, center-block is now mx-auto, representing margin: 0 auto; for centering display:block elements. Bootstrap 4 now has a d-block class too so an inline element can be made display:block like this..

<img src=".." class="d-block mx-auto" >

Also see: Center the content inside a column in Bootstrap 4

回答2:

Bootstrap 4 (as of 2017-08-16) will use d-block and to center you use mx-auto.

回答3:

Bootstrap 4 does not have center-block Instead, I use d-block mx-auto which sets display to block, and left and right margins to auto.

来源：https://stackoverflow.com/questions/38251191/bootstrap-4-center-block-unable-to-center