* {
    padding: 0;
    margin: 0;
    text-align: none;
    list-style: none;
    box-sizing: border-box;
}
nav {
    background-color: rgb(6, 53, 68);
    height: 80px;
    width: 100%;

}

label.logo {
    color: aliceblue;
    font-size: 2rem;
    line-height: 80px;
    padding: 0 10%;
    font-weight: 400;
}

<div class="mobile-menu-icon">
  <span></span>
  <span></span>
  <span></span>
</div>


nav ul {
    float: right;
    margin-right: 5%;
}

nav ul li {
    display: inline-block;
    line-height: 80px;
    margin: 0 0.5rem;
}

nav ul li a {
    color: white;
    font-size: 1rem;
    padding: 0.5rem 1rem;
    border-radius: 3px;
    text-transform: capitalize;
}

a.active, a:hover{
    background: rgb(6, 53, 68);
    transition: .5s;
}
.checkbtn{
    font-size: 2rem;
    color: white;
    float: right;
    line-height: 80px;
    margin-right: 2rem;
    cursor: pointer;
}
    #check {
        display: none;
    }
#menu-toggle:checked + nav {
  display: block;
}

.menu-icon {
  display: block;
  width: 40px;
  height: 40px;
  background-color: #333;
  color: #fff;
  text-align: center;
  line-height: 40px;
  cursor: pointer;
  border-radius: 4px;
}

/* dropdown menu */
.dropdown_menu{
    display: none;
    position: absolute;
    right: 2rem;
    top: 60px;
    height: 0;
    width: 300px;
 /*   background: ; */
    bacdrop fiter: blur(15px);
    overflow: hidden;
    transition: height .2s cubic-bezier(0.175, 0885, 0.32, 1.275);
}

.dropdown_menu.open{
    height: 240px;
}

.dropdown_menu li{
    padding: 0.7rem;
    display: flex;
    align-item: center;
    justify-content: center;
}

.dropdown_menu .action_btn{
    width: 100%;
    display: flex;
    justify-content: center;
    
    /*RESPONSIVE DESIGN */
    


       /*media queries */

    @media (max-width: 858px) {
        /* hide the navigation menu */
        nav ul {
            dispay: none;
        }
        
       /*Show the mennu icon*/   
        .checkbtn{
            display: block;
        }
        
        /*Style the expanded menu*/
        ul{
            position: fixed;
            width: 100%;
            height: 100vh;
            background: #2c3e50;
            top: 80px;
            left: -100%;
            text-align: center;
            transition: all .5s;
        }
        nav ul li{
            display: block;
            margin: 2rem 0;
            line-height: 2rem;
        }
        na ul li a{
            font-size: 1.5rem;
        }
        a:hover, a.active{
            background: none;
            color: #9cb3c5;
        }
        
        /* show the expanded menu the icon i clicked */
        #check: checked ~ ul{
            left: 0;
        }
        
        /*styles for larger screens */
        @media (min-width: 859px) {
            label.logo{
                font-size: 2.5rem
                padding-left: 5%;
            }
        
            nav ul li a{
                font-size: 1.2rem;
            }
            
            /* styles for even larger screen */
            @media (min-width: 1200px) {
                label.logo{
                    font-size: 3rem;
                    padding-left: 10%;
                }
                
                /*update the height and padding of the logo */
                label.logo{
                    font-size: 30px;
                    padding; 0 50px;
                    line-height: 50px;
                    
                    /* update the font size and padding of links */
                    nav ul li a{
                        font-size: 16px;
                        padding; 7px 10px;
                    }
                    
                    /* update the height of the section */
                    
                    section{
                        height: calc(100vh - 50px);
                    }
                    
                    /* adjust the height and padding of the header and footer , iframe*/
                    @media screen and (max-width: 768px) {
                    
                    header {
                        height: 50px;
                    }
                    footer {
                        height: 30px;
                        font-size: 14px;
                    }
                    
              
                         /*--iframe media query--*/
                    iframe {

                        width: 100%;

                        height: 80px;

                    }
                        
                        /* make iframe and images responsive */
                        
                        iframe, img {
                            max-width: 100%
                            height: 80px;
                            padding-bottom: 56.25%
                        }

/* show the menu when the check button is checked */
        #check:checked ~ ul{
            left: 0;
        }
    }
section{
    background: url(assets/cross.jpg) no-repeat;
    background-size: cover;
    height: calc(100hv - 80px);
}


                               /* mobile icon */
                    .mobile-menu-icon {
  display: block;
  width: 30px;
  height: 25px;
  position: relative;
  margin: 0 auto;
  cursor: pointer;
}

.mobile-menu-icon span {
  display: block;
  position: absolute;
  height: 3px;
  width: 100%;
  background: #333;
  border-radius: 9px;
  opacity: 1;
  left: 0;
  transform: rotate(0deg);
  transition: all 0.25s ease-in-out;
}

.mobile-menu-icon span:nth-child(1) {
  top: 0px;
}

.mobile-menu-icon span:nth-child(2), 
.mobile-menu-icon span:nth-child(3) {
  top: 10px;
}

.mobile-menu-icon span:nth-child(3) {
  top: 20px;
}

.mobile-menu-icon.open span:nth-child(1) {
  top: 10px;
  transform: rotate(45deg);
}

.mobile-menu-icon.open span:nth-child(2) {
  opacity: 0;
}

.mobile-menu-icon.open span:nth-child(3) {
  top: 10px;
  transform: rotate(-45deg);
}