Opacity in CSS makes cards on my page overlap the navbar

I am building a website for a crypto coin meme, the problem is that my navbar doesn’t overlap some of the links and cards I created that have ‘opacity’ argument in CSS. I want to make my navbar overlap everything when I scroll down.

Example photo https://imgur.com/a/Ipd1lOT

HTML code:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">

    <link rel="preconnect" href="https://fonts.googleapis.com">
    <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
    <link href="https://fonts.googleapis.com/css2?family=Montserrat:wght@200&family=Roboto&family=Roboto+Slab&display=swap" rel="stylesheet">

    <link rel="stylesheet" href="CSS/navbar.css">
    <link rel="stylesheet" href="CSS/buttons.css">
    <link rel="stylesheet" href="CSS/details.css">
    <link rel="stylesheet" href="CSS/container.css">
    <link rel="stylesheet" href="CSS/container2.css">
    <link rel="stylesheet" href="CSS/container3.css">
    <link rel="stylesheet" href="CSS/footer.css">

    <link rel="icon" type="image/gif/png" href="assets/shitcoin_logo.png">
    
    <title>Shitcoin - Worst crypto currency</title>
</head>
<body>
<header>
    <div class="Nav-Container">

        <a href=""><img class="logo" src="assets/shitcoin_logo.png" alt=""></a>

      <nav class="navbar">
        <ul>
            <li class="navbar-links"><a href="">Home</a></li>
            <li class="navbar-links"><a href="">About us</a></li>
            <li class="navbar-links"><a href="">Stake</a></li>
            <li class="coinprice"><img src="assets/shitcoin_logo.png" alt=""><p>:&nbsp;&nbsp;$0.00213</p></li>
            <li><a href="#" class="walltet">Connect Wallet</a></li>
        </ul> 
      </nav>
    </div>
</header>
     <div class="container1"> 
        <div class="aboutcointext"> 
            <h1>Welcome to the <span>THUNDER</span> project homepage</h1>
            <h2>Worst cypto coin available on the market!</h2>
            <a href="" class="buycoin">Buy Thunder (THD)</a>
        </div>
        <div class="aboutcoinlinks">
            <a href="" class="fb">Facebook</a>
            <a href="" class="insta">Instagram</a>
            <a href="" class="twitter">Twitter</a>
        </div>
    </div>
    <div class="details">Why you should <span>NOT</span> invest in us?</div>
    <div class="container2">
        <div class="reason1">
            <img src="assets/man_on_toilet.png" alt="">
            <h3>Reason 1:</h3>
            <p>We have very little to no experience in the crypto world</p>
        </div>
        <div class="reason2">
            <img src="assets/just_toilet.png" alt="">
            <h3>Reason 2:</h3>
            <p>This coin is made as a joke and should not be taken seriously</p>
        </div>
        <div class="reason3">
            <img src="assets/money-pngrepo-com.png" alt="">
            <h3>Reason 3:</h3>
            <p>Your capital is at risk and we are not responsible for your money</p>
        </div>
    </div>
    <div class="mining_details">You can mine <span>Shitcoin</span> but we don't guarantee you'll make money</div>
    <div class="container3">
        <div class="">
            <p>Compact tool made by us to help you mine easier:</p>
            <a href="" class="minerbutton">Download THD miner</a>
        </div>
    </div>

<footer>
    <div class="footer-container">
        <h2>Contact Us</h2>
        <ul>
            <li><a href="">Support</a></li>
            <li><a href="">Email</a></li>
            <li><a href="">About Us</a></li>
        </ul>
    </div>
    <div class="footer-container">
        <h2>FAQ</h2>
        <ul>
            <li><a href="">How to buy?</a></li>
            <li><a href="">How to sell?</a></li>
            <li><a href="">How to mine THD?</a></li>
            <li><a href="">More...</a></li>
            
        </ul>
    </div>
</footer>    

</body>
</html>

CSS code for navbar:

body{
    margin: 0;
    padding: 0;
    font-family: 'Roboto', sans-serif;
    background: linear-gradient(0deg, rgba(47,48,48,1) 0%, rgba(73,80,87,1) 100%);
    /* background-color: #495057; */
    color: white;
}
header{
    position: sticky;
    top: 0;
    background-color: #ADB5BD;
}
header::after{
    content: '';
    display: table;
    clear:both;
}
.Nav-Container{
    width: 80%;
    margin: 0 auto;
}
.logo{
    width: 5rem;
    float: left;
}
.navbar{
    float: right; 
    /* text-align: center; */
}
.navbar ul{
    list-style: none;
    margin:0;
    padding:0;
}
.navbar li{
    display: inline-block;
    margin-left: 70px;
    padding-top: 31px;

    position: relative;
}
.navbar a{
    color: #495057;
    text-decoration: none;
    text-transform: uppercase;
}
.navbar a:hover{
   color: white;
}
.navbar-links::before{
    content:'';
    display: block;
    height: 5px;
    background-color: white;

    position: absolute;
    top: 0;
    width: 0%;

    transition: all ease 250ms;
}
.navbar-links:hover::before{
    width: 100%;
}
.navbar img{
    float:left;
    width: 2rem;
    position: relative;
    bottom: 7px;
}
.navbar p{
    display: inline;
}
.wallet{
    display: inline;
    padding: 5px 5px;
    border: 1px solid #495057;
    border-radius: 7px;
}

CSS code for social media links:

.aboutcoinlinks{
    display:flex;
    flex-direction: row;
    flex-wrap: wrap;
}
.aboutcoinlinks a{
    align-self: flex-start;
    margin-left:10px;
    padding: 20px 15px;
    text-decoration: none;
    color: white;
    text-align: center;
    background-color: black;
    opacity:70%;
    transition: all ease 250ms;
}
.aboutcoinlinks a:hover{
    opacity: 100%;
}

.aboutcoinlinks .fb{
    padding: 20px 15px;
    background-color: #4267B2;
    border: 1px solid #4267B2;
    border-radius: 10px;
}
.aboutcoinlinks .insta{
    padding: 20px 15px;
    background: linear-gradient(45deg, #f09433 0%,#e6683c 25%,#dc2743 50%,#cc2366 75%,#bc1888 100%); 
    border: 1px solid linear-gradient(45deg, #f09433 0%,#e6683c 25%,#dc2743 50%,#cc2366 75%,#bc1888 100%);;
    border-radius: 10px;
}
.aboutcoinlinks .twitter{
    padding: 20px 15px;
    background-color: #1DA1F2;
    border: 1px solid #1DA1F2;
    border-radius: 10px;
}