body {
  background-color: #000;
  background-image: url("index_backgroundimage.jpg");
  background-position: center;
  background-attachment: fixed;
  background-repeat: no-repeat;
  background-size: cover;
  color: white;
  font-family: "Arial", sans-serif;
  margin: 0;
  padding: 0;
  text-align: center;
}

.header {
  background-color: rgba(31, 69, 110, 0.95);
  padding: 30px;
  border-radius: 10px;
  box-shadow: 0px 0px 10px rgba(255, 255, 255, 0.3);
}

h1 {
  color: white;
  font-size: 30px;
  margin: 0;
  padding-bottom: 10px;
}

h2 {
  color: #ddd;
  font-size: 18px;
  margin: 0;
}

.exercise-container {
  background-color: rgba(31, 69, 110, 0.9);
  padding: 20px;
  width: 20%;
  margin: 50px auto;
  border-radius: 10px;
  box-shadow: 0px 0px 10px rgba(255, 255, 255, 0.3);
}

.exercise-container h3 {
  margin-bottom: 5px;
  font-size: 20px;
  color: white;
}

.exercise-container.large {
  width: 80%;
  max-width: 800px;
}

.table-wrapper {
  overflow-x: auto;
  max-width: 100%;
}

.number-table {
  width: 100%;
  border-collapse: collapse;
  background-color: rgba(255, 255, 255, 0.9);
  color: #1F456E;
  font-size: 18px;
  font-weight: bold;
  text-align: center;
  border-radius: 10px;
  overflow: hidden;
}

.number-table td {
  border: 1px solid #1F456E;
  padding: 10px;
}

.number-table tr:nth-child(even) {
  background-color: #ddd;
}

.exercise-list {
  list-style: none;
  padding: 0;
}

.exercise-list li {
  margin: 10px 0;
}

.exercise-list a {
  display: block;
  background-color: white;
  color: #1F456E;
  padding: 10px;
  text-decoration: none;
  font-weight: bold;
  border-radius: 5px;
  transition: 0.3s;
}

.exercise-list a:hover {
  background-color: #ddd;
}