Ion-slides min-height

ionic-v1
1

Hi, I have a ion-slides like this one in my :

<div id="slider">
                <ion-slides  options="options" slider="data.slider">
                    <ion-slide-page ng-repeat="img in immobile.ImmagineImmobile">
                        <img src="{{img.ImmagineUrl}}">
                    </ion-slide-page>
                </ion-slides>
            </div>

If I don’t set this CSS

.swiper-container {
  min-height:280px;
}

“slides” is not showed.

Is this normal ? Thanks.