Angular/html : How do you apply z-index between two divs from different files/components?

Question

I work on Angular and I have two different html files from two DIFFERENT COMPONENTS and I call the code of the first html file using the selector. In the first html I have a dropdown menu but it gets covered by the div of the second html file.

HTML of the FIRST file

 <div class="dropdown">
              <button class="dropbtn"> login
              </button>
              <div class="dropdown-content dropdown-menu-center">
                <a href="#">login as user </a>
                <a href="#">login as admin </a>
              </div>
            </div>

CSS of the FIRST file

.dropbtn {
  color: black;
  padding: 16px;
  font-size: 16px;
  position: relative;
  border: none;
  margin-right: 100px;
  background: rgba(246, 246, 246, 0);
}

.dropdown {
  position: relative;
  display: inline-block;
}



 .dropdown-menu-center {
    left: 28% !important;
    right: auto !important;
    text-align: center !important;
    transform: translate(-50%, 0) !important;
    }

.dropdown-content {
  display: none;
  position: relative;
  background-color: #f6f6f6;
  min-width: 170px;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  top: 55px;
  z-index: 1;
}
.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}

HTML of the SECOND file (calling the first file with the selector app-first-file>

<app-first-file></app-first-file>   
  <div class="rectangle">
    hello world
</div>

CSS of the SECOND file

.rectangle {
    width: 1200px;
    position: relative;
    background: rgba(255, 255, 255);
    margin-right: 80px;
    border-bottom-left-radius: 20px;
    border-bottom-right-radius: 20px;
    z-index: -1;
  }

I used z-index both in dropdown-content in file1 and rectangle in file2 but it doesn't work

NB: I can't mix them in the same file/component due to work requirements.

Answer 1

I think 1st CSS file . You should try "z-index" attribute in class:

dropdown

Or both class:

dropdown-content

dropdown-menu-center

.dropdown-content.dropdown-menu-center{
     z-index:1;
}