Display automatically set to block in JavaScript function

I have a problem in a JavaScript function in which i handle slider properties. I have 3 slide with class .slide and everytime i "choose" one of them i set it with .active-slide class. The problem is that also if the display property of active-slide is table, when i set this class, it automatically changes to block and i can't understand why. P.s. i'm using also bootstrap. I'm posting here the part of my code related to this problem:

HTML:

<div class="slider">
        <div class="slide active-slide">        
            <div class="container up">
                <div class="row">
                    <div class="col-md-5 slide-text">
                        <h1 class="slide-title">whatuwant</h1>
                        <p class="slide-par">whatuwant</p>
                        <a href="#" class="slide-link">whatuwant</a>
                    </div>
                    <div class="col-md-7" id="first-slide-image">
                        <img src="whatuwant"/>
                    </div>
                </div>
            </div>
        </div>

        <div class="slide">        
            <div class="container up">
                <div class="row">
                    <div class="col-md-5 slide-text"> 
                        <h1 class="slide-title">whatuwant</h1>
                        <p class="slide-par">whatuwant</p>
                    </div>
                    <div class="col-md-7" id="second-slide-image">
                        <img src="whatuwant"/>
                    </div>
                </div>
            </div>
        </div>

        <div class="slide">        
            <div class="container up">
                <div class="row">
                    <div class="col-md-5 slide-text">
                        <h1 class="slide-title">whatuwant</h1>
                        <p class="slide-par">whatuwant</p>
                    </div>
                    <div class="col-md-7 slide-image" id="third-slide-image">
                        <img src="whatuwant"/>
                    </div>
                </div>
            </div>
        </div>
    </div>

CSS:

.container {
    width: 1024px;    
}

.up{  
    display: table-cell;
    vertical-align: middle;  
    max-width: 1024px;
    max-height: 470px;
}

.row{
    width: 1024px;
    margin: 0 auto;
    max-width: 1024px;
}

.slider {
    position: relative;
    width: 100%;
    height: 470px;
}

.slide {
    display: none;
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.active-slide{
    display: table;   
}

JavaScript:

$(document).ready(function() {
 $('.buttonfornextslide').click(function() {
    var currentSlide = $('.active-slide');
    var nextSlide = currentSlide.next();

    if(nextSlide.length === 0) {
      nextSlide = $('.slide').first();
    }

    currentSlide.fadeOut(600).removeClass('active-slide');
    nextSlide.fadeIn(600).addClass('active-slide');
  });


  $('.buttonforpreviousslide').click(function() {
    var currentSlide = $('.active-slide');
    var prevSlide = currentSlide.prev();

    if(prevSlide.length === 0) {
      prevSlide = $('.slide').last();
    }

    currentSlide.fadeOut(600).removeClass('active-slide');
    prevSlide.fadeIn(600).addClass('active-slide');
  });
});

I tried to simplify it to the maximum i could. If the question wasn't clear: how can i hold the .active-slide display property to table?