Here is a general solution, using CSS only, which I have verified to work.

@media print {
  body * {
    visibility: hidden;
  }
  #section-to-print, #section-to-print * {
    visibility: visible;
  }
  #section-to-print {
    position: absolute;
    left: 0;
    top: 0;
  }
}

Alternative approaches aren’t so good. Using display is tricky because if any element has display:none then none of its descendants will display either. To use it, you have to change the structure of your page.

Using visibility works better since you can turn on visibility for descendants. The invisible elements still affect the layout though, so I move section-to-print to the top left so it prints properly.