Side menu + submenu - resize to see responsive

<div class="side-menu" id="responsive-nav">
  <div class="side-menu__wrapper">

    <div class="side-menu__block">

      <div class="side-menu__block-heading">
      Heading here
      </div>

      <ul class="side-menu__list">
        <li class="side-menu__list-item side-menu__list-item--has-submenu">
          <a href="#" class="side-menu__list-link toggle">Link with submenu</a>
          <div class="menu__children menu__children--side-menu">
            <div class="submenu__wrapper submenu__wrapper--side-menu">
              <div class="submenu submenu--side-menu">
                <ul class="submenu__list submenu__list--side-menu">
                  <li class="submenu__list-item submenu__list-item--side-menu">
                    <a href="#">Submenu link</a>
                  </li>
                  <li class="submenu__list-item submenu__list-item--side-menu">
                    <a href="#">Submenu link</a>
                  </li>
                </ul>
              </div>
            </div>
        </li>
        <li class="side-menu__list-item">
          <a href="#" class="side-menu__list-link">Link here</a>
        </li>
      </ul>

    </div>
  </div>
</div>