A [scalar](/styles/css_units/scalar) can be any of the following:

 - a fixed number of cells (e.g., `10`);
 - a fractional proportion relative to the sizes of the other widgets (e.g., `1fr`);
 - a percentage relative to the container widget (e.g., `50%`);
 - a percentage relative to the container width/height (e.g., `25w`/`75h`);
 - a percentage relative to the viewport width/height (e.g., `25vw`/`75vh`); or
 - the special value `auto` to compute the optimal size to fit without scrolling.