I have a problem in css code background color

in this part every thing is working exept this : background: rgba(255, 255, 255, 0.7);

Html Code:

 <nav id="header">
        <div class="nav-logo">
            <p class="nav-name">Om</p>
            <span>.</span>
        </div>
        <div class="nav-menu" id="myNavMenu">
            <ul class="nav_menu_list">
                <li class="nav_list">
                    <a href="#home" class="nav-link">Home</a>
                    <div class="circle"></div>
                </li>
                <li class="nav_list">
                    <a href="#about" class="nav-link">About</a>
                    <div class="circle"></div>
                </li>
                <li class="nav_list">
                    <a href="#projects" class="nav-link">Projects</a>
                    <div class="circle"></div>
                </li>
                <li class="nav_list">
                    <a href="#contact" class="nav-link">Cantact</a>
                    <div class="circle"></div>
                </li>
            </ul>
        </div>
        <div class="nav-button">
            <button class="btn">Download Cv<i class="fa-solid fa-file"></i></button> 
            
        </div>
        <div class="nav-menu-btn">
        <i class="fa-solid fa-bars" onclick="myMenuFunction()"></i>
        </div>
     </nav>

Css code:

nav{
    position: fixed;
    display: flex;
    justify-content: space-between;
    width: 100%;
    height: 90px;
    line-height: 90px;
    background: var(--body-color);
    padding-inline: 9vw;
    transition: .3s;
    z-index: 100;
}
.nav-logo{
    position: relative;
}

.nav-name{
    font-size: 20px;
    font-weight: 600;
    color: var(--text-color-third);
}
.nav-logo span{
    position: absolute;
    top: -10px;
    right: -20px;
    font-size: 3em;
    color: var(--text-color-second);
}
.nav-menu, .nav_menu_list{
    display: flex;
}
.nav-menu, .nav_list{
   list-style: none;
   position: relative;
}

.nav-link{
    text-decoration: none; 
    color: var(--text-color-second);
    font-weight: 500;
    padding-inline: 15px;
    margin-inline: 20px;
}

.nav-menu-btn{
     display: none;
}

.nav-menu-btn i{
    font-size: 28px;
    cursor: pointer;
}

@media only screen and (max-width:900px) {
    .nav-button{
        display: none;
    }
    .nav-menu.responsive{
        left: 0;
    }

    .nav-menu{
        position: fixed;
        top: 80px;
        left: 100%;
        flex-direction: column;
        justify-content: center;
        align-items: center;   
        background: rgba(255, 255, 255, 0.7);
        backdrop-filter: blur(50px);
        width: 100%;
        min-height: 450px;
        height: 90vh;
        transition: .3s;
    }

    .nav_menu_list{
        margin-top: 100px;
        flex-direction: column;
    }
    .nav-menu-btn{
        display: flex;
        align-items: center;
        justify-content: center;
    }

Javascript code:

function myMenuFunction(){
       var menuBtn = document.getElementById("myNavMenu");

       if(menuBtn.className === "nav-menu"){
          menuBtn.className += "responsive";
       } else {
        menuBtn.className = "nav-menu";
       }
   }

/* ----ADD SHADOW ON NAVIGATION BAR WHILE SCROLLING  -----*/
   window.onscroll = function() {headerShadow()};

   function headerShadow() {
      const navHeader =document.getElementById("header");

      if(document.body.scrollTop > 50 || document.documentElement.scrollTop > 50 ) {
         navHeader.style.boxShadow = "0 1px 6px rgba(0, 0, 0, 0.1)";
         navHeader.style.height = "70px";
         navHeader.style.lineHeight = "70px";
      } else {
         navHeader.style.boxShadow = "none";
         navHeader.style.height = "90px";
         navHeader.style.lineHeight = "90px";

      }
   }

It will not have any effect when the background is white.

Happy coding

i tryed another colors but still dosnt work , the problem that is when i make the pages sizes smaller my nav bar has to be hidden and nav menu button it will be shown so when i open the nav menu my backgroud will be blur and white so the elements in background will look blurry and the menu items will appear in front of me