*{
    box-sizing: border-box;
}
body{
    margin: 0;    
    font-size: 1rem; 
    line-height: 1;
    color: whitesmoke;  
    overflow-x: hidden;
    font-family: 'Gill Sans', 'Gill Sans MT', Calibri, 'Trebuchet MS', sans-serif;
    background-color: #2E2E2E;
}
.header {  
    height: 100vh;
    display: flex;
    align-items: center;
    background-color: rgb(0, 204, 255);
}
.content{  
    max-width: 20rem;
     
    margin: auto;
    text-align: center;
}
.header-video{
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh;
    overflow: hidden;
}
.header-video video{
    min-width: 100%;
    min-height: 100%;
}
.header-overlay{
    height: 100vh;
    width: 100vw;
    position: absolute;
    top: 0;
    left: 0;
    background: #2E2E2E;
    z-index: 1;  
    opacity: .85;      
}
.header-content
{
z-index: 2;
}
.header-content h1{
font-size: 100px;
margin-bottom: 0;
font-family: 'Satisfy', cursive;
}
.header-content p{
    font-size: 1.5rem;
    display: block;
    padding-bottom: 2rem;
        
    
}
@media (max-width:960px){
    .content{
        padding: 0 3rem 0 3rem;
    }

}
<!--barra de navegacion-->
nav{    
    z-index: 2;     
}
nav ul{    
  list-style-type: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
  background-color: #333333;
}
nav li {    
    float: left;      
}
nav a{
  display: block;
  color: white;
  text-align: center;
  padding: 16px;
  text-decoration: none;
}
li a:hover {
    background-color: #111111;
}
.navbar-nav.navbar-center {
    position: absolute;
    left: 50%;
    transform: translatex(-50%);
    
}