Where is this style from?

Question

css

I use slick slider. I overridden the width in some of its classes, but at startup (when the slider is opened for the first time), the width of 1 photo is 0. If you change the browser width, start scrolling, the width will become the one I set. What is the problem?
In HTML I directly asked, through other classes I applied, everything is the same

<div class="overlay a6" style="visibility: hidden">
        <div class="main a6-photo" style="visibility: hidden">
            <div class="sl">
                
                <div class="sl__slide" style=" background: url({{ 1|retlink:'6 1' }})
                        no-repeat center center; background-size: cover;">
                </div>
                <div class="sl__slide" style=" background: url({{ 1|retlink:'6 2' }})
                        no-repeat center center; background-size: cover;">
                </div>
                
            </div>
        </div>
    </div>

Answer 1

no need to touch native slick blocks. Insert your custom blocks inside an empty div

<div class="slider">
    <div>
        <!-- А тут свой блок -->
    </div>
    <div>
        <!-- А тут свой блок -->
    </div>
</div>