*,
*::before
*::after{
  margin: 0;
  padding: 0;
  box-sizing: inherit;
}


body{

  background-image: url("Media/sternenhimmel.jpg");
  background-attachment: fixed;
  background-position: POSITION;
  background-repeat: repeat settings;

}

a{
  text-decoration: none;
}

ul{
  list-style: none;
}
p{
  font-size: 1.6rem;
  margin: 5rem;
}

.row{
  margin: 0;
}
section{
  padding: 5rem 0;
}


html{
  font-family: 'Arial', sans-serif;
  font-size: 10px;
}
.col_left {

  background-color: grey;
  opacity: 0;

}

.col_main {

  background-color: tan;

}

/*.Test1 {

  margin: 50px;
  float: left;

}

.Test2 {

  margin: 50px;
  float: right;

}

.Test3 {

  margin: 50px;
  float: left;

}

.Test4 {

  margin: 50px;
  float: right;

}
*/
.Box1 {


margin: 5rem;
position: relative;
top: 10%;
left: 5%;
}

.Box2 {

margin: 5rem;
position: relative;
top: -9%;
left: 60%;
}

.Box3 {

margin: 5rem;
position: relative;
top: -10%;
left: 5%;
}

.Box4 {

margin: 5rem;
position: relative;
top: -29%;
left: 60%;


}

.quizbtn{
  color: #007bff;
  position: absolute;
  top: 48%;
  left: 42%;
  border-radius: 5px;
  font-size: 2rem;
  padding: 10px 20px;
  border: 2px solid #007bff;
}

.quizbtn:hover{
  background-color: #fff;
}

.col_right {

  background-color: grey;
  opacity: 0;

}

.navbar-brand{
  width: 2.5%;
  max-width: 75%;
  height: auto;
}
audio{

}
nav{
  width: 102%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 2rem 5;
  border-bottom: 1px solid rgba(255,255,255,.2);
}

.nav-brand{
  width: 1.5rem;
}


.nav-item{
  margin: 2rem 0;

}

.nav-link{
  font-size: 1.6rem;
  text-transform: uppercase;
  color: rgba(0,0,0,.7);
}

ul li a {
  position: relative;
  display: block;
  text-decoration: none;
  font-family: "Arial";
  font-size: 2rem;;
  color: #ecf0f1;
  text-transform: uppercase;
  margin-left: 2rem;
  margin-right: 2rem;
  padding: 4px 0;
  transition: 0.5s;
}
ul li a::after {
  position: absolute;
  content: "";
  width: 100%;
  height: 3px;
  top: 100%;
  left: 0;
  background: #ff7000;
  transition: transform 0.5s;
  transform: scaleX(0);
  transform-origin: center;
}
ul li a:hover {
  color: white;
}
ul li a:hover::after {
  transform: scaleX(1);
  transform-origin: right,left;
}
* {

  font-family: Arial, sans-serif;

}
h1{
  font-size: 6rem;
}

@media only screen and (max-width: 800px){
  /*For Tablets*/

  .col_left{

    width: 15%;

  }

  .col_main {

    width: 70%;

  }

  .col_right {

    width: 15%;

  }

}


@media only screen and (max-width: 500px){
 /*For mobile phones*/


 nav{
   position:fixed;
   width:103.2%;
 }

   img{
     width: 75%;

   }
 .navbar-brand{
   width: 4.5%;
 }
body{
  background-image: none;
  background-color: tan;
}

button{
  position: fixed;
  top: .7%;
  left: 90%;
  color: white;
}
.navbar-toggler{
  position: fixed;
  left: 90%;
}

ul li a::after{
  transform-origin: right;
  width: 13%;
}
ul li a:hover::after {
  transform-origin: left;
}

.quizbtn{
  font-size: 2rem;
  width: 50%;
  padding: 5px 10px;
  position: relative;
  top: 35rem;
  left: 1rem;
}

.Box1{
  position: absolute;
  top: 10rem;
  left: -3rem;
}


.Box2{
  position: absolute;
  top: 30rem;
  left: -3rem;
}

.Box3{
  position: absolute;
  top: 50rem;
  left: -3rem;
}


.Box4{
  position: absolute;
  top: 70rem;
  left: -3rem;
}