Best Practice: Specify Font Sizes in Relative Units (em or %)

These days, browsers can enlarge fonts even if you specify the size in so-called "absolute" units such as px or pt, but it is still considered best practice to specify the font size in relative units such as em or %, to account for older browsers, and to allow for the greatest potential amount of flexibility in enlarging the font within the browser.

Good Example

font: .9em/1.7em Arial, Verdana, sans-serif;


Use Underline (text-decoration: underline) Only on Links

Users expect underlined content to be links.


Don't Rely on Strikethrough (<del> or text-decoration: line-through) or insert (<ins>)

Screen readers do not notify listeners when text has a strikethrough line crossing it out, so you can't use <del> or text-decoration: line-through to convey that text has been deleted. This is extremely unfortunate for those who work with legal documents, because strikethrough is the common way of marking deleted text in legal documents. Similarly, the insert tag (<ins>) — which underlines text as a way to show new text to be inserted — is equally useless to screen reader users.


Ensure Text on the Page Can Be Resized, Ideally up to at least 200%

Users with partial and low vision often choose to enlarge the fonts on their browser in order to make text on the web easier to read.


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