Problem with div block background

Hello There,
I am still new to programming with HTML and CSS, and i have a small problem. I have put a div block inside a hero image, which works perfectly fine, however the background of that div-block is not transparent. I have tried to counter this with using a background-color: transparent; which isn’t working.
NOTE: The following code has some german text in it, as it is my main language.
My HTML:

        Dreisam Republik

                    <a href="#">Forum</a>
                    <a href="#">Impressum</a>
                    <a href="#">Über uns</a>

            <a href="#">Login

              Die Dreisam Republik

                Die Dreisam Republik ist ein Ein-Wöchiges Projekt, wo das DFG/LFA eine eigene Wirtschaft aufbaut

And here is my CSS:@import url('https://fonts.googleapis.com/css2?family=Montserrat:wght@500&display=swap');
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  background-color: #24252a;
}

li, a, button {
  font-family: "Montserrat", sans-serif;
  font weight: 500;
  font-size: 16px;
  color: #edf0f1;
  text-decoration: none;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 30px 10%;
}
.nav__links {
  list-style: none;
}

.nav__links li {
  display: inline-block;
  padding: 0px 20px;
}

.nav__links li a {
  transition: all 0,3s ease 0s;
}

.nav__links li a:hover {
  color: #0088a9
}

button {
  padding: 9px 25px;
  background-color: rgba(0,136,169,1);
  border: none;
  border-radius: 50px;
  cursor: pointer;
  transition: all 0,3s ease 0s;
}

button:hover {
  background-color: rgba(0,136,169,0.8);
}

h1 {
  margin-top: 40px;
  margin-left: 65px;
  margin-bottom: 20px;
}
.Banner {
  background:url("DRHI.png");
  padding-top: 40%;
  }
.Banner_Content {
  text-align: center;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: white;
  background-color: transparent;
  text-decoration: none;
}

I would appreciate some help regarding my Problem
Have a nice Day!