Style issues with b-collapse and css - css

Question

what I am trying to do is modify the style of my b-collapse since by default it has a vertical style that I think and what I want is to give my menu a horizontal style
This is how I implement it:
<div style="background-color:white;">
<b-collapse id="collapse-cat-lvl1-469">
<div data-cat-acc="473" class="grid-item parent-lvl-2">
<a class="link -1 grid-sty-1" href="#" target="_self" data-menu-item-id="473">
<span class="text">GTI</span>
</a>
</div>
<div data-cat-acc="474" class="grid-item parent-lvl-2">
<a class="link sty-1 grid-sty-1" href="#" target="_self" data-menu-item-id="474">
<span class="text">Pets</span>
</a>
</div>
</b-collapse>
</div>
You can modify <b-collapse id = "collapse-cat-lvl1-469"> in if this: collapse-cat-lvl1-469 ???
What I intend is to give it better style with CSS, or some way that I can see my menu horizontally and not vertically
.navbar-greetings, .login-section{display: none}
#menu-header.collapse:not(.show){
display: block;
}
#menu-header{
position: fixed;
top: 25px;
max-width: 83%;
margin: 0 auto;
left: 8.32%;
.panel{
button{
display: block;
color: white;
font-size: 13px;
font-family: 'VWHead-Bold';
}
}
#accordion-mbl-menu{
display: flex;
}
}