*{
 margin:0;
 padding:0;
}
.wrapper{

width:1000px;
margin:60px auto;
}
body{
 background-image:url(https://cdn.pixabay.com/photo/2019/09/18/21/12/dark-4487690_960_720.jpg);
 background-size: cover;
}
li{ 
 padding:15px ;
 color:white;
 background-color:rgba(255,255,255,0.3);
 font-size:18px; 
 text-align:center;
}
li:hover{
background-color:rgba(255,255,255,0.5); 
}
.flex-nav ul li{
 list-style-type: none; 
 flex: 3;
}
.flex-nav ul{
display:flex;
border:1px solid black;
}
.flex-nav .soshel{
flex: 1;
}
section{
 text-align:center;
 color:white;
 padding:20px;
 background-color:rgba(0, 0, 0, 0.7);
 margin: 20px 0;
 font-weight:100;
}
footer{
 text-align:center;
 color:white;
 padding:20px;
 background-color:rgba(0, 0, 0, 0.7);
 margin: 20px 0;
 font-weight:100;
}

@media all and (max-width: 800px){
 body{
  background-image: url(https://p4.wallpaperbetter.com/wallpaper/9/519/764/mountains-best-for-desktop-background-wallpaper-preview.jpg);
 }
}