I fully believe that the principle of proximity is the main design tool (though contrast in size helps, of course). You could forget about color and still lay out things clearly and beautifully.
The primary rule is incredibly simple, as mentioned in the article: there should be more space around an element than inside of it―then the eye will perceive the element as cohesive.
This, then, is applied on all levels of a layout: letter shapes and kerning, line spacing, headers and paragraphs spacing, blocks layout, page margins. Even architecture uses this principle―not too surprisingly, since it just describes the workings of visual perception.
Beginner designers sometimes try to remember a bunch of rules for optimal line spacing, header and paragraph spacing, page margins, etc. They can go for years not knowing why particular proportions work, and if elements change they begin to calculate this stuff anew in pixels, or just get lost as to what to do now. Meanwhile, if you go to the principles, you learn to see the proximity, and all spacing becomes obvious to you.
P.S. A bit ironic that the article uses line spacing too close to double. By the way, on Macs and phones, Matthew Butterick's ‘Practical Typography’ website is absolutely perfect in both spacing and contrast, at least with the default Valkyrie font. I'm immeasurably envious of this feat, as I have no idea how to achieve such mastery. Link: https://practicaltypography.com
The primary rule is incredibly simple, as mentioned in the article: there should be more space around an element than inside of it―then the eye will perceive the element as cohesive.
This, then, is applied on all levels of a layout: letter shapes and kerning, line spacing, headers and paragraphs spacing, blocks layout, page margins. Even architecture uses this principle―not too surprisingly, since it just describes the workings of visual perception.
Beginner designers sometimes try to remember a bunch of rules for optimal line spacing, header and paragraph spacing, page margins, etc. They can go for years not knowing why particular proportions work, and if elements change they begin to calculate this stuff anew in pixels, or just get lost as to what to do now. Meanwhile, if you go to the principles, you learn to see the proximity, and all spacing becomes obvious to you.
P.S. A bit ironic that the article uses line spacing too close to double. By the way, on Macs and phones, Matthew Butterick's ‘Practical Typography’ website is absolutely perfect in both spacing and contrast, at least with the default Valkyrie font. I'm immeasurably envious of this feat, as I have no idea how to achieve such mastery. Link: https://practicaltypography.com