Proportion

The relationship of one measure to another. It is the quiet mathematics that makes a thing feel resolved before you can say why.

Proportion is relationship made visible: this measure against that one, the part against the whole. Certain ratios recur because they resolve, the way certain intervals in music resolve. A layout can be full of good parts and still feel wrong; almost always the ratios between them are the fault.

We fix proportions before styling anything. Column to gutter, headline to body, image to caption: settle these as ratios and the design holds together at any size. The reader will never name what feels resolved about a page. That namelessness is proportion doing its work.