title: Tab box sized by biggest panel content in pure CSS
body: <p>Using floats, flexbox or a table, there are different methods to size two adjacent blocks to the same height or to the same width, dependent on their contents <strong>without using JavaScript.</strong></p>
  
  <p>I wonder if there is a way to achieve the same for panels of a tab box, of which only one is visible at a time.</p>
  
  <p>So if for example a panel is empty, its size (or at least its background) should be extended to the size of the biggest panel in the stack of panels.</p>
  
  <p>My intention is to prevent elements below or beside the tab box to jump to different positions when the tab is switched, but I don't want to assume anything about the dimensions of the panel contents since they are dynamic.</p>