* {
  box-sizing: border-box;
}

body {
  background-color: #f5f5f5;
  font-family: Arial, sans-serif;
}

header, main {
  max-width: 960px;
  margin: 0 auto;
}

header {
  padding: 32px 0;
  text-align: center;
}

h1 {
  font-size: 48px;
  font-weight: bold;
  color: #333;
  margin-bottom: 16px;
}

p {
  font-size: 18px;
  color: #666;
}

main {
  padding: 32px 0;
}

section {
  padding: 32px;
  border-radius: 8px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

.leaderboard ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.leaderboard li {
  display: flex;
  align-items: center;
  border-bottom: 1px solid #ddd;
  padding: 16px 0;
}

.leaderboard img {
  width: 50px;
  height: 50px;
  border-radius: 50%;
  margin-right: 16px;
}

.leaderboard h3 {
  font-size: 24px;
  font-weight: bold;
  color: #333;
  margin-bottom: 4px;
}

.leaderboard p {
  font-size: 16px;
  color: #666;
}

.leaderboard a {
  color: #007bff;
  text-decoration: none;
}

.leaderboard a:hover {
  text-decoration: underline;
}

.testimonials h2 {
  font-size: 28px;
  font-weight: bold;
  color: #333;
  margin-bottom: 24px;
}

.testimonials blockquote {
  padding: 24px;
  border-radius: 8px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
  background-color: #fff;
}

.testimonials p {
  font-size: 18px;
  color: #666;
  margin-bottom: 8px;
}

.testimonials cite {
  font-size: 14px;
  color: #999;
  font-style: italic;
}

.contact h2 {
  font-size: 28px;
  font-weight: bold;
  color: #333;
  margin-bottom: 24px;
}

.contact form {
  display: flex;
  flex-direction: column;
}

.contact input, .contact textarea {
  width: 100%;
  padding: 12px;
  border: 1px solid #ddd;
  border-radius: 4px;
  margin-bottom: 16px;
}

.contact input:focus, .contact textarea:focus {
  outline: none;
  border-color: #007bff;
}

.contact textarea {
  resize: vertical;
}

.contact button {
  background-color: #007bff;
  color: #fff;
  border: none;
  padding: 12px 24px;
  border-radius: 4px;
  cursor: pointer;
  transition: background-color 0.2s ease-in-out;
}

.contact button:hover {
  background-color: #0062cc;
}

.tabs {
  display: flex;
  justify-content: space-between;
  border-bottom: 1px solid #ddd;
  margin-bottom: 32px;
}

.tabs label {
  padding: 16px;
  cursor: pointer;
  transition: background-color 0.2s ease-in-out;
}

.tabs label:hover {
  background-color: #f5f5f5;
}

.tabs input[type="radio"] {
  display: none;
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}