/* Contenedor */
.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 1rem;
}

/* Títulos */
h2 {
  font-size: 2rem;
  margin-bottom: 1rem;
  text-align: center;
}

h5 {
  font-size: 1.25rem;
  margin-top: 1.5rem;
  margin-bottom: .75rem;
}

/* Fila */
.row {
  display: flex;
  flex-wrap: wrap;
  margin-left: -0.5rem;
  margin-right: -0.5rem;
}

/* Columnas */
.col-md-3,
.col-md-4,
.col-md-6,
.col-md-9,
.col-md-12 {
  padding-left: 0.5rem;
  padding-right: 0.5rem;
  box-sizing: border-box;
}

/* Ancho en escritorio */
.col-md-3 { flex: 0 0 25%; max-width: 25%; }
.col-md-4 { flex: 0 0 33.3333%; max-width: 33.3333%; }
.col-md-6 { flex: 0 0 50%; max-width: 50%; }
.col-md-9 { flex: 0 0 75%; max-width: 75%; }
.col-md-12 { flex: 0 0 100%; max-width: 100%; }

/* Márgenes */
.mb-2 { margin-bottom: .5rem; }
.mb-3 { margin-bottom: 1rem; }
.mb-4 { margin-bottom: 1.5rem; }
.mt-4 { margin-top: 1.5rem; }

/* Labels */
.form-label {
  display: inline-block;
  margin-bottom: .25rem;
  font-weight: 500;
}

/* Inputs y textarea */
.form-control,
.form-select {
  display: block;
  width: 100%;
  padding: .375rem .75rem;
  font-size: 1rem;
  line-height: 1.5;
  color: #495057;
  background-color: #fff;
  background-clip: padding-box;
  border: 1px solid #ced4da;
  border-radius: .25rem;
  transition: border-color .15s ease-in-out,box-shadow .15s ease-in-out;
}

.form-control:focus,
.form-select:focus {
  border-color: #80bdff;
  outline: 0;
  box-shadow: 0 0 0 .2rem rgba(0,123,255,.25);
}


/* Responsive: en pantallas <= 768px, columnas al 100% */
@media (max-width: 768px) {
  .col-md-3,
  .col-md-4,
  .col-md-6,
  .col-md-9 {
    flex: 0 0 100%;
    max-width: 100%;
  }
}