How do i get a side menu to resize in dawn theme

[raujunk]

Im trying to have a side menu for different categories and i found some code that turned my menu in the header vertical and to the side but it dosent resize with the window and overlaps with the other content. Im using the dawn theme and here is the code that i used 

.header__inline-menu {
    position: absolute;
    top: 35%;
    left: 185px;
}
.list-menu--inline {
    display: flex;
    flex-wrap: wrap;
    flex-direction: column;
}

[raujunk]

I found the code from another post https://community.shopify.com/c/shopify-design/dawn-theme-move-menu-to-the-the-left-sidebar/m-p/1359...

[raujunk]

vptestshop.myshopify.com