body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  margin: 0;
  background: #f8f9fa;
  color: #343a40;
  transition: background 0.3s ease;
}

header {
  background: linear-gradient(to right, #2c3e50, #4ca1af);
  color: white;
  padding: 1rem 2rem;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

header h1 {
  margin: 0;
  font-size: 2rem;
  letter-spacing: 1px;
}

nav ul {
  list-style: none;
  padding: 0;
  display: flex;
  gap: 1rem;
  margin-top: 0.5rem;
}

nav a {
  color: white;
  text-decoration: none;
  font-weight: 500;
  transition: color 0.3s, border-bottom 0.3s;
  border-bottom: 2px solid transparent;
}

nav a:hover {
  color: #ffcc00;
  border-bottom: 2px solid #ffcc00;
}

main {
  padding: 2rem;
}

section {
  margin-bottom: 3rem;
  background: white;
  padding: 2rem;
  border-radius: 12px;
  box-shadow: 0 4px 10px rgba(0,0,0,0.08);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

section:hover {
  transform: translateY(-5px);
  box-shadow: 0 6px 18px rgba(0,0,0,0.15);
}

section h2 {
  color: #007bff;
  margin-bottom: 1rem;
}

.button {
  display: inline-block;
  margin-top: 1rem;
  padding: 0.75rem 1.5rem;
  background: #007bff;
  color: white;
  text-decoration: none;
  border-radius: 6px;
  font-weight: bold;
  transition: background 0.3s, transform 0.2s;
}

.button:hover {
  background: #0056b3;
  transform: scale(1.05);
}

/* Botón destacado (calculadora) */
.boton-destacado {
  background-color: #ffcc00;
  color: #000;
  font-weight: bold;
  padding: 0.75rem 1.5rem;
  border-radius: 8px;
  text-decoration: none;
  display: inline-block;
  transition: background 0.3s, transform 0.3s;
}

.boton-destacado:hover {
  background-color: #ffc107;
  transform: scale(1.05);
}

/* Sección destacada (calculadora importante) */
.destacado {
  background-color: #fff8dc;
  border: 2px solid #ffcc00;
  padding: 2rem;
  margin-bottom: 2rem;
  border-radius: 10px;
  text-align: center;
  box-shadow: 0 0 15px rgba(255, 204, 0, 0.2);
}

/* Botones de rutina estilo tarjeta */
.grid-rutinas {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
}

.btn-rutina {
  display: block;
  background: #2c3e50;
  color: #FFD700;
  text-decoration: none;
  padding: 1.5rem;
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s, background 0.3s, color 0.3s;
}

.btn-rutina:hover {
  background: #FFD700;
  color: #2c3e50;
  transform: translateY(-5px);
}

.btn-rutina h3 {
  margin-top: 0;
  margin-bottom: 0.5rem;
}

input, select, button {
  display: block;
  width: 100%;
  margin-top: 0.5rem;
  padding: 0.6rem;
  font-size: 1rem;
  border: 1px solid #ccc;
  border-radius: 6px;
  margin-bottom: 1rem;
  transition: border-color 0.3s;
}

input:focus, select:focus {
  border-color: #007bff;
  outline: none;
}

button {
  background: #28a745;
  color: white;
  border: none;
  cursor: pointer;
  transition: background 0.3s, transform 0.2s;
}

button:hover {
  background: #218838;
  transform: scale(1.02);
}

footer {
  background: #343a40;
  color: white;
  text-align: center;
  padding: 1rem;
  margin-top: 2rem;
  font-size: 0.9rem;
}

#resultado {
  font-weight: bold;
  margin-top: 1rem;
  color: #28a745;
  transition: color 0.3s ease;
}