* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Arial, sans-serif;
  background-color: #f4f6f8;
  color: #222;
}

.header {
  padding: 32px 16px;
  text-align: center;
  background-color: #1f2937;
  color: white;
}

.header h1 {
  margin-bottom: 8px;
}

.container {
  max-width: 1000px;
  margin: 32px auto;
  padding: 0 16px;
}

.exercise-card {
  background-color: white;
  padding: 24px;
  border-radius: 12px;
  margin-bottom: 24px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.exercise-card h2 {
  margin-top: 0;
}

button {
  padding: 10px 16px;
  border: none;
  border-radius: 8px;
  background-color: #2563eb;
  color: white;
  cursor: pointer;
  font-weight: bold;
  transition: background-color 0.2s ease;
}

button:hover {
  background-color: #1d4ed8;
}

button:focus {
  outline: 3px solid #93c5fd;
  outline-offset: 2px;
}

.button-group {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

pre {
  margin-top: 16px;
  padding: 16px;
  background-color: #111827;
  color: #d1fae5;
  border-radius: 8px;
  overflow-x: auto;
}

.footer {
  padding: 24px 16px;
  text-align: center;
  background-color: #1f2937;
  color: white;
  font-size: 14px;
}

.footer p {
  margin: 4px 0;
}