body {
  font-family: 'Segoe UI', sans-serif;
  margin: 0;
  padding: 0;
  background: #f6f7fb;
  color: #333;
}

header {
  background: #1a73e8;
  color: white;
  padding: 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

h1 {
  margin: 0;
  font-size: 1.2rem;
}

select {
  padding: 0.4rem;
  font-size: 1rem;
  border-radius: 6px;
  border: none;
}

main {
  max-width: 800px;
  margin: 2rem auto;
  padding: 1rem;
  background: white;
  border-radius: 10px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

#descripcion {
  margin-bottom: 1.5rem;
  font-size: 1.1rem;
}

#btnGenerar {
  background: #1a73e8;
  color: white;
  border: none;
  padding: 0.7rem 1.2rem;
  border-radius: 6px;
  cursor: pointer;
}

#btnGenerar:hover {
  background: #0f5ed7;
}

#ejercicio {
  margin-top: 1.5rem;
  font-size: 1.3rem;
  min-height: 4rem;
  border: 1px solid #ddd;
  padding: 0.5rem;
  border-radius: 6px;
  background: #f9f9f9;
}

.excelTable {
  border-collapse: collapse;
  width: 100%;
  max-width: 700px;
  margin: 20px auto;
  font-family: Arial, sans-serif;
}

.excelTable th, .excelTable td {
  border: 1px solid #666;
  padding: 8px 12px;
  text-align: center;
}

.excelTable th {
  background-color: #4CAF50;
  color: white;
}

.excelTable tr:nth-child(even) {
  background-color: #f2f2f2;
}

.excelTable tr:hover {
  background-color: #ddd;
}