* {
  margin: 0;
  padding: 0;
  font-family: Cambria, Cochin, Georgia, Times, "Times New Roman", serif;
}

.banner {
  height: auto;
  width: 100%;
}

nav {
  margin-top: -4px;
  background-color: lightgreen;
}

a:hover {
  text-decoration: none;
  color: #000;
}

a {
  text-decoration: none;
  color: #000;
}

nav ul {
  display: flex;
  flex-direction: row;
  justify-content: center;
}

nav ul li {
  list-style: none;
  margin: 3px 5px;
  padding: 10px;
  font-size: 20px;
}

nav ul li:hover {
  background-color: orange;
  border-radius: 12px;
  transition: 0.2s;
}

footer {
  background-color: aqua;
  padding: 15px 0;
  position: absolute;
  width: 100%;
  font-size: 18px;
  margin-top: 15px;
}

.btn {
  background-color: #4caf50;
  border: 2px solid #4caf50;
  border-radius: 10px;
  color: #fff;
  padding: 12px 32px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
  font-size: 16px;
  cursor: pointer;
  text-transform: uppercase;
  font-family: "Trebuchet MS", "Lucida Sans Unicode", "Lucida Grande",
    "Lucida Sans", Arial, sans-serif;
  font-weight: 600;
  line-height: 1;
  margin: 4px;
}

.btn:hover {
  background-color: #4fcf50;
  transition: 0.3s;
}

.btn:focus {
  background-color: #f76d37;
  transition: 0.4s;
}

.class_title {
  text-align: center;
  font-size: 20px;
  margin: 10px 0;
}

.books {
  display: flex;
  flex-direction: column;
}

.book {
  width: 150px;
  height: 150px;
  display: block;
  margin: 0 auto;
}

.btn-wrap {
  margin: 0 auto;
}

.math {
  background-color: rgba(227, 245, 150, 0.856);
  margin: 2% 20%;
  padding: 30px;
  border-radius: 15px;
}

body {
  background-color: #aefad5c9;
}

#the-canvas {
  border: 1px solid black;
  direction: ltr;
  width: 80%;
  margin: 10px;
  padding: 10px;
}