How can I put my menus beside ocher in a header?

I am trying to make a dropdown menu, it’s my first time doing it and I’m experimenting with it. The problem that I’m facing is this:

As you can see, the principal menus are showing in a list. I have tried displaying them as flex and other attempts, but it seems like the header is making a limitation to them and I don’t know how to put them beside each other. (Clarification: ‘Notificaciones’ and ‘Usuario’ are main menus and ‘Mi Perfil’ is a submenu that comes from ‘Usuario’ (parent))

Here is my code:

<header>
  <div class="header-text">
    <h1 class="titulo-logo">Lorem</h1>
  </div>

  <nav class="nav">
    <ul>
      <li><a href="">Notificaciones</a></li>
      <li>
        <a href="">Usuario</a>
        <ul>
          <li><a href=""></a>Mi Perfil</li>
        </ul>
      </li>
    </ul>
  </nav>
</header>

And my CSS:

* {
    text-decoration: none;
    list-style: none;
  }
  body {
    margin: 0px;
    padding: 0px;
    font-family: roboto;
  }
  .header-text {
    position: relative;
    margin: 2px 6px 2px 4px;
    cursor: pointer;
  }
  .header-icons {
    width: 32px;
    margin: 2px 0px 2px 0px;
    cursor: pointer;
  }
  header {
    display: flex;
    justify-content: space-between;
    background-color: rgb(20, 33, 61);
    color: white;
    height: 30px;
    align-items: center;
    padding: 6px;
    position: static;
  }
  .nav li a {
    padding: 4px;
    background-color: red;
    list-style: none;
    display: inline-block;
    float: right;
  }

Thank you so much in beforehand!

>Solution :

First the <li> should have display: inline-block for being arranged in a row. It has nothing to do with the header.
Second, the position of the sub menu (ul ul) needs to be absolute within a li with position: relative.

white-space: nowrap will make the element not wrap when the width is larger than the parent element’s width.

* {
    text-decoration: none;
    list-style: none;
  }
  body {
    margin: 0px;
    padding: 0px;
    font-family: roboto;
  }
  .header-text {
    position: relative;
    margin: 2px 6px 2px 4px;
    cursor: pointer;
  }
  .header-icons {
    width: 32px;
    margin: 2px 0px 2px 0px;
    cursor: pointer;
  }
  header {
    display: flex;
    justify-content: space-between;
    background-color: rgb(20, 33, 61);
    color: white;
    height: 30px;
    align-items: center;
    padding: 6px;
    position: static;
  }
  .nav li a {
    padding: 4px;
    background-color: red;
    list-style: none;
    display: inline-block;
    float: right;
  }
  
  /* added css */
  ul li{
    display: inline-block;
    position: relative;
    white-space: nowrap
  }
  ul ul{
    position: absolute;
    right:0;
    top:100%
  }

<header>
  <div class="header-text">
    <h1 class="titulo-logo">Lorem</h1>
  </div>

  <nav class="nav">
    <ul>
      <li><a href="">Notificaciones</a></li>
      <li>
        <a href="">Usuario</a>
        <ul>
          <li><a href="">Mi Perfil</a></li>
        </ul>
      </li>
    </ul>
  </nav>
</header>