index.css

body {
  margin: 0px;
  font-family: 'Open Sans', sans-serif;
  background-color: black;
}
h1 {
  margin-top:20px;
  margin-left: 50px;
  padding: 0px;
  font-size: 40px;
}
section {
  display: block;
  background-position: center center;
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-size: cover;
  width: 100%;
  height: 1000px;
  position: relative;
}

.container {
  color: white;
  position: absolute;
}

h2 {
  margin: 0px;
  color: #fff;
  background-color: rgba(0,0,0,0.5);
  padding: 20px;
}

.section1{
  background-color: white;
}

.section1 .container{
  top: 250px;
  left: 100px;
}

.section2{
  background-color: #111;
}

.section2 .container{
  top: 300px;
  right: 200px;
}

.section3{
  background-color: #333;
}

.section3 .container{
  top: 400px;
  left: 250px;
}

#menu1 {
  position: fixed;
  top: 0px;
  height: 100px;
  width: 100%;
  background-color: black;
  z-index: 1;
  opacity: 0;
}
#menu1 h1 {
  color: white;
}

#menu2 {
  position: fixed;
  top: 0px;
  height: 100px;
  width: 100%;
  background-color: white;
  z-index: 1;
  opacity: 0;
}

#menu3 {
  position: fixed;
  top: 0px;
  height: 100px;
  width: 100%;
  background-color: red;
  z-index: 1;
  opacity: 0;
}