ul {
    margin: 0;
    padding: 20px;
    margin-left: 10px;
   }

   
   *{
       font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    }

   nav{
       width: 100%;
       height: 60px;
       background-color: rgb(54, 54, 54);
       float: left;
   }
   ul li{
    list-style: none;
    float: left;
    height: 50px;
   }
   
   ul li a{
       text-decoration: none;
       padding: 0 20px;
       font-style:initial;
       color:whitesmoke ;
       font-size: large;
   }
   .menu > li > a:hover{
       border-bottom: 7px;
       border-bottom-style: solid;
       border-bottom-color: white  ;
       border-bottom-width: 2px;
       background-color: rgb(194, 196, 196);
       color: black;
       border-radius: 1cm;
       transition: all .5s;
   }
   
   .menu > li{
       display: inline-block;
       position: static;
   }
   
   body{
       background-color: rgb(194, 196, 196);
       background-image: url('./media/nano.png');
       background-repeat: no-repeat;
       background-size: cover;
       position: static;
       overflow-y: auto;
       overflow-x: hidden;
   }
   
   .background-image{
       height: 100%;
       float: left;
   }
   .Title{
       border-bottom: 7px;
       border-bottom-style: solid;
       border-bottom-color: white  ;
       border-bottom-width: 2px;
       background-color: rgb(194, 196, 196);
       color: black;
       border-radius: 1cm;
       transition: all .25s;
       
   }
   .Home{
       height: 300px;
       padding: 7px;
       margin: 50px;
   }
   .Topic{
       height: 300px;
       padding: 3px;
       margin: 50px;
   }
   
   .About{
       height: 300px;
       padding: 7px;
       margin: 50px;
   }
   
   .Contact{
       height: 300px;
       padding: 7px ;
       margin: 50px;
       border-bottom: 7px;
       border-bottom-style: solid;
       border-bottom-color: white  ;
       border-bottom-width: 2px;
       background-color: rgb(194, 196, 196);
       color: black;
       border-radius: 1cm;
   }
   .Net{
    height: 300px;
    padding: 7px;
    margin: 50px;
}
   
   .stair{
       position: absolute ;
       background: #333;
       width: 80%;
       visibility: hidden;
       opacity: 0;
       transition: opacity 1s;
       border-bottom-left-radius: 1cm;
       border-bottom-right-radius: 1cm;
       margin-top: 15px;
   }
   .stair li a{
       display: block;
       padding: 20px;
       color: #fff;
       text-decoration: none;
       height: 0px;
   }
   
   .menu li:hover .stair{
       display: block;
       visibility: visible;
       opacity: 2;
       float: left;
       z-index: 1;
       width: 150px;
   }
   .stair > li > a:hover{
       border-bottom: 1px;
       border-bottom-style: solid;
       border-bottom-color: white  ;
       border-bottom-width: 3px;
       transition: all .25s;
       display: block;
       z-index: 2;
       float: left;
       opacity: 1;
   }
   .logo{
       width: 40px;
   }
   .logo2{
       height: 10px;
   }   
   
   .container{
    position: relative;
    display:block;
    justify-content: center;
    align-items: center;
    width: 100%;
    height: 100%;
    padding: 20px 100px;
    margin-top: 0px;
    float: left;
   }
   .container:after{
    content: '';
    position: relative;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
   }
   .contact-box{
        max-width: 850px;
        display: block;
        justify-content: center;
        text-align: center;
        background-color: #fff;
        border-radius: 1cm;
   }
   .left{
    height: 100%;
   }
   .right{
    padding: 25px 40px;
   }
h2{
    position: relative;
    padding-bottom: 10px;
    margin-bottom: 10px;
}
h2:after{
    content: '';
    position:absolute;
    left: 50%;
    bottom: 0;
    transform: translateX(-50%);
    height: 4px;
    width: 50px;
    border-radius: 2px;
    background-color: #2ecc71;
}
.field{
    width: 100%;
    padding: 0.5rem 1rem;
    outline: none;
    border: 2px solid;
    background-color: rgba(230, 230, 230, 0.6);
    font-size: 1.1rem;
    margin-bottom: 22px;
    transition: .3s;
}
.field:focus{
    background-color: #fff;
    border: 2px solid;
}
.area{
    min-height: 150px;
}
.btn{
    width: 100%;
    padding: 0.5rem 1rem;
    font-size: 1.1rem;
    background-color: #2ecc71;
    cursor: pointer;
    outline: none;
    border: none;
    transition: .3s;
    color: #fff;
}
.btn:hover{
    background-color: #27ae60;
}
.main{
    overflow-y: hidden;
    padding-bottom: 10px;
}
.footer{
    border: none;
    color: white;
    position: sticky;
    height: 80px;
    margin-top: 0px;
    margin-bottom: 0;
    float: left;
    width: 100%;
}
.instagram{
    height: 50px;
    margin-left: 500px;
}
.facebook{
    height: 50px;
    margin-left: 50px;
}
.twitter{
    height: 50px;
    margin-left: 50px;
}