:root{
  font-size: 20px;
  --color-yellow:#FCB700;
  --color-orange:#E88212;
}
* {
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
}
.center{text-align: center;}
a{text-decoration: none;}
.top-img{
  position: fixed;
  top:0;
  width:100%;
  height:100%;
  z-index:-1;
  opacity: 0.3;
}
nav a{
  position:fixed;
  bottom:20px;
  right: 10px;
  margin:0;
  padding:3px 13px 0 13px;
  height: 2rem;
  background-color: transparent;
  color:var(--color-orange);
  border: solid 5px var(--color-orange);
  border-radius: 10%;
}