index.css

* {
  margin: 0px;
  padding: 0px;
}
body {
  background-color: rgb(209,255,203);
}
.nav {
  background-color: rgb(22,38,42);
}
.nav ul {
  display: flex;
  justify-content: left;
  align-items: center;
  align-content: center;
}
li {
  list-style: none;
  text-decoration: none;
  margin: 9px;
}
li a:hover {
  color: yellow;
}
.form-control {
  margin: 7px;
  padding: 9px;
  display: flex;
  flex-wrap: wrap;
}
#btn {
  margin: 9px;
}

/*
.addbook {
  width: 100%;
  height: 53vh;
  display: flex;
  align-content: center;
  align-items: center;
  justify-content: center;
*/

.booking {
  height: 55vh;
  background-image: radial-gradient(#0d677e, #0867a2, #00ccff);
display: flex;
  align-content: center;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;

}
/*

#btn {
  padding: 9px;
  border-radius: 9px;
  outline: none;
  background-color: rgb(55,12,121);
  color: white;
}
*/