* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Arial, sans-serif;
  background: #f5f7fb;
  color: #222;
}

.container {
  max-width: 900px;
  margin: 40px auto;
  padding: 0 20px 40px;
}

h1 {
  margin-bottom: 10px;
}

.intro {
  margin-bottom: 30px;
  color: #555;
}

.pregunta {
  background: #fff;
  border-radius: 12px;
  padding: 20px;
  margin-bottom: 20px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
}

.enunciado {
  margin: 0 0 15px 0;
  font-size: 1.1rem;
}

.opciones {
  display: grid;
  gap: 10px;
}

.opcion {
  width: 100%;
  text-align: left;
  padding: 12px;
  border: 2px solid #ccc;
  border-radius: 10px;
  background: #fff;
  cursor: pointer;
  font-size: 1rem;
  transition: 0.2s;
}

.opcion:hover:not(:disabled) {
  background: #eef3ff;
}

.opcion:disabled {
  cursor: default;
}

.correcta {
  background: #d4edda;
  border-color: #28a745;
  color: #155724;
}

.incorrecta {
  background: #f8d7da;
  border-color: #dc3545;
  color: #721c24;
}

.explicacion {
  display: none;
  margin-top: 15px;
  padding: 12px;
  border-left: 4px solid #4a6cf7;
  background: #eef3ff;
  border-radius: 6px;
  line-height: 1.5;
}

button:not(.opcion) {
  background: linear-gradient(135deg, #3b82f6, #2563eb);
  color: white;
  border: none;
  border-radius: 14px;
  padding: 12px 22px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  box-shadow: 0 6px 18px rgba(37, 99, 235, 0.25);
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.2s ease;
}

button:not(.opcion):hover {
  transform: translateY(-1px);
  box-shadow: 0 10px 22px rgba(37, 99, 235, 0.32);
  background: linear-gradient(135deg, #2563eb, #1d4ed8);
}

button:not(.opcion):active {
  transform: translateY(0);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.22);
}