Web Typography and Readability: A Practical Design Guide

A body-text font needs a medium width and clean letterforms so long paragraphs do not tire the eye; a heading font can carry more of the brand's character, since short text carries less readability risk. The two do not have to come from the same font family; two well-paired fonts usually work better than forcing one font to do both jobs.

If a thin, decorative font gets used for body text on a law firm's site, long passages like contract terms become hard to read; the decorative font can stay on headings while body text switches to something plainer.

A clear scale with three or four levels (heading, subheading, body, small note) works better than five or six barely different font sizes; it gives both consistency and a clear rule for a developer to follow. Each step in the scale should be noticeably bigger or smaller than the last; sizes too close together, like 16px and 17px, do not register visually, they just add clutter.

Too many characters on a line and the eye struggles to find the start of the next one; too few and the eye keeps jumping lines, breaking the reading rhythm. A workable range is sixty to eighty characters per line, which means text should sit in a limited column on a wide screen, not stretch across the full width.

If a flooring manufacturer's technical documentation page lets text stretch across the whole screen, lines on a wide monitor can run past two hundred characters; the fix is pinning content to a fixed column width and letting the rest of the space stay blank or hold an image.

Before a font gets picked, every accented character used in headings and body text should be tested with real copy, not just an English placeholder. Some fonts render the mark over ğ far too small, others cut the tail under ş short; details like this go unnoticed until the text is enlarged on screen.

• Headings and body text previewed with real Turkish or English content, whichever the site uses
• Accented characters checked at several sizes
• Bold weight checked for the same characters
• Readability at small mobile sizes tested separately

Some visitors increase text size through their browser settings; a site built with fixed pixel values blocks that preference from working. Defining sizes in flexible units, such as rem, lets a visitor's own setting carry through to the site; it is a small, practical step for accessibility and for visitors with reduced vision.

In a traditional setup, every font weight, light, regular, bold, is its own separate file; a variable font carries every weight inside a single file, and the browser generates whichever weight it needs from that one file. That means one download instead of five or six.

For a brand using three or four different weights, a variable font setup both cuts total file size and gives a designer the freedom to reach for an in-between weight, something between regular and bold, say; most current browsers support this, but a fallback is worth keeping if older-browser support still matters.

If the numbers in a pricing table or a spec sheet do not line up column by column, the eye struggles to compare them. That usually happens because a font defaults to proportional figures, where each digit takes up a different width; turning on tabular figures makes every digit the same width, and the columns line up properly.

On a generator manufacturer's spec table, power ratings sitting unaligned next to each other become noticeably more readable the moment this setting is switched on; in most modern fonts it is a single line of CSS.

The setting is not limited to tables; the same difference shows up anywhere numbers sit side by side for comparison, a price list, a date and time display.