header ,footer{background-color:grey; color:yellow;}
a:link{}
a:visited{}
a:hover{}
a:active{}

.firstHeading { font-family:Times New Roman, Times, serif;}

* {box-sizing: border-box;}

body {
    background-image: url("Cool-Light-Grey-background-fantastic-imago-creative-studio-video-production-2.jpg");
  max-width: 1200px;
  margin: 20px auto;
  padding: 0 100px;
  overflow-x: hidden;
}

.header {
  overflow: hidden;
  background-color: #f1f1f1;
  padding: 20px 10px;
}

.header a {
  float: left;
  color: black;
  text-align: center;
  padding: 12px;
  text-decoration: none;
  font-size: 18px; 
  line-height: 25px;
  border-radius: 4px;
}

.header a.logo {
  font-size: 50px;
  font-weight: bold;
}

.header a:hover {
  background-color: #ddd;
  color: black;
}

.header a.active {
  background-color: dodgerblue;
  color: white;
}

.header-right {
  float: right;
}

@media screen and (max-width: 500px) {
  .header a {
    float: none;
    display: block;
    text-align: left;
  }
  
  .header-right {
    float: none;
  }
}